diff --git a/Makefile b/Makefile
index 95c7716..0b25637 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CFLAGS = -Isaturn
 
-OPT ?= -O3
+OPT ?= -Og
 LIB = ./saturn
 
 GEN_PYTHON_SOURCE = $(wildcard tools/source/*.py) $(wildcard tools/generate/*.py)
@@ -35,11 +35,12 @@ SRC += input.cpp
 SRC += vram.cpp
 SRC += font.cpp
 SRC += graphic.cpp
-SRC += menu.cpp
 SRC += number.cpp
 SRC += pokemon_instance.cpp
 SRC += ailment.cpp
-SRC += menu/stats.cpp
+SRC += party.cpp
+SRC += window/window.cpp
+SRC += window/menu.cpp
 
 DEP = $(patsubst %.cpp,%.cpp.d,$(SRC))
 
diff --git a/battle.hpp b/battle.hpp
new file mode 100644
index 0000000..e1b81d5
--- /dev/null
+++ b/battle.hpp
@@ -0,0 +1,6 @@
+enum battle_action {
+  fight,
+  swap_pokemon,
+  item,
+  run,
+};
diff --git a/cell_offset.hpp b/cell_offset.hpp
new file mode 100644
index 0000000..8690ba9
--- /dev/null
+++ b/cell_offset.hpp
@@ -0,0 +1,5 @@
+struct cell_offset
+{
+  static constexpr int32_t x = (320 - 160) / (2 * 8);
+  static constexpr int32_t y = (240 - 144) / (2 * 8);
+};
diff --git a/derived/font.png b/derived/font.png
index ac4957a..240d9ff 100644
Binary files a/derived/font.png and b/derived/font.png differ
diff --git a/graphic.hpp b/graphic.hpp
index 0b67d4a..8fe522c 100644
--- a/graphic.hpp
+++ b/graphic.hpp
@@ -4,7 +4,7 @@
 
 #include "coordinates.hpp"
 #include "start_size.hpp"
-#include "render_map.hpp" // for cell_offset
+#include "cell_offset.hpp" // for cell_offset
 #include "vdp2.h"
 
 #include "pokemon_instance.hpp"
diff --git a/input.hpp b/input.hpp
index 4a077fb..14a55dc 100644
--- a/input.hpp
+++ b/input.hpp
@@ -57,4 +57,5 @@ struct event {
   static inline bool cursor_up()    { return input_flopped(input.up   ) >= 1; }
   static inline bool cursor_down()  { return input_flopped(input.down ) >= 1; }
   static inline bool button_a()     { return input_flopped(input.a ) == 1; }
+  static inline bool button_b()     { return input_flopped(input.b ) == 1; }
 };
diff --git a/main.cpp b/main.cpp
index 929dceb..66e631c 100644
--- a/main.cpp
+++ b/main.cpp
@@ -14,24 +14,17 @@
 #include "vram.hpp"
 #include "font.hpp"
 
-#include "gen/maps.hpp"
+#include "gen/tilesets.hpp"
 #include "gen/sprites.hpp"
-#include "map_objects.hpp"
-
-#include "coordinates.hpp"
-#include "render_map.hpp"
-#include "actor.hpp"
-#include "ledge_tiles.hpp"
-
-#include "graphic.hpp"
-#include "menu.hpp"
-
 #include "pokemon.hpp"
-#include "pokemon_instance.hpp"
+#include "gen/maps.hpp"
+#include "actor.hpp"
+#include "player.hpp"
 
-#include "menu/stats.hpp"
+#include "cell_offset.hpp"
 
-static int32_t pokemon_raw_index = 0;
+#include "window/window.hpp"
+#include "window/window_stack.hpp"
 
 struct draw_t {
   struct {
@@ -46,10 +39,8 @@ struct draw_t {
 };
 
 struct state_t {
-  enum map_t::map map;
-  enum map_t::map last_map;
   draw_t draw;
-  actor_t player;
+  player_state_t player[1];
 };
 
 static state_t state = { map_t::pallet_town, map_t::last_map, 0 };
@@ -203,6 +194,7 @@ void render_sprites(const offset_t& offset)
 {
   uint32_t ix = 2;
 
+  /*
   const uint32_t animation_frame = ((state.player.frame & 0b1000) != 0) * 3;
   render_sprite(ix,
 		spritesheet_t::red,
@@ -212,11 +204,6 @@ void render_sprites(const offset_t& offset)
 		state.player.y_offset());
   ix++;
 
-  render_pokemon(ix, static_cast<enum pokemon_t::pokemon>(pokemon_raw_index),
-		 {0, 0},
-		 true); // invert horizontally
-  ix++;
-
   const object_t& obj = map_objects[state.map];
   for (uint32_t i = 0; i < obj.object_length; i++) {
     const object_event_t& event = obj.object_events[i];
@@ -229,6 +216,7 @@ void render_sprites(const offset_t& offset)
 		  -4);
     ix++;
   }
+  */
 
   constexpr uint16_t top_x = 80 - 1;
   constexpr uint16_t top_y = 48 - 1;
@@ -262,249 +250,39 @@ void render_sprites(const offset_t& offset)
 
 void render_map()
 {
-  const map_t& map = maps[state.map];
-  const uint32_t base_pattern = state.draw.base_pattern.tilesets[map.tileset];
-  vdp2.reg.PNCN0 = PNCN0__N0PNB__1WORD | PNCN0__N0CNSM | PNCN0__N0SCN((base_pattern >> 10) & 0x1f);
+  //const map_t& map = maps[state.map];
+  //const uint32_t base_pattern = state.draw.base_pattern.tilesets[map.tileset];
+  //vdp2.reg.PNCN0 = PNCN0__N0PNB__1WORD | PNCN0__N0CNSM | PNCN0__N0SCN((base_pattern >> 10) & 0x1f);
 
   for (int32_t y = (0 - 1); y < (9 + 2); y++) {
     for (int32_t x = (0 - 2); x < (10 + 2); x++) {
+      /*
       render_screen(base_pattern,
 		    map,
 		    state.player.world,
 		    {x, y}
 		    );
-    }
-  }
-
-  vdp2.reg.BGON = BGON__N0ON | BGON__N0TPON | BGON__N1ON;
-}
-
-constexpr inline world_t direction_offset(const world_t& world, const enum actor_t::direction dir)
-{
-  switch (dir) {
-  default: [[fallthrough]];
-  case actor_t::up:    return {world.x    , world.y - 1};
-  case actor_t::down:  return {world.x    , world.y + 1};
-  case actor_t::left:  return {world.x - 1, world.y    };
-  case actor_t::right: return {world.x + 1, world.y    };
-  }
-}
-
-constexpr inline uint8_t get_tile_ix(const map_t& map, const world_t& coord)
-{
-  // keep this synchronized with render_screen()
-
-  const uint8_t block_ix = get_block(map, coord.to_block());
-  const tileset_t& tileset = tilesets[map.tileset];
-  const uint8_t * block_start = &(tileset.blockset.start)[block_ix * 4 * 4];
-  const int32_t quadrant_x = 2 * (coord.x & 1);
-  const int32_t quadrant_y = 2 * (coord.y & 1);
-
-  const int32_t block_row = 4 * (quadrant_y + 1);
-  const uint8_t tile_ix = block_start[block_row + quadrant_x];
-
-  return tile_ix;
-}
-
-constexpr inline enum actor_t::collision collision(const map_t& map,
-						   const world_t& world,
-						   enum actor_t::direction direction)
-{
-  const world_t coord = direction_offset(world, direction);
-  uint8_t collision_tile_ix = get_tile_ix(map, coord);
-
-  const tileset_t& tileset = tilesets[map.tileset];
-  for (uint32_t i = 0; i < tileset.collision.size; i++) {
-    if (tileset.collision.start[i] == collision_tile_ix)
-      return actor_t::passable;
-  }
-
-  // check ledge_tile pairs
-
-  uint8_t actor_tile_ix = get_tile_ix(map, world);
-
-  for (uint32_t i = 0; i < ledge_tiles_length; i++) {
-    const ledge_tile_t& lt = ledge_tiles[i];
-    if (direction == lt.direction
-	&& actor_tile_ix == lt.actor
-	&& collision_tile_ix == lt.collision) {
-      return actor_t::jump;
-    }
-  }
-
-  return actor_t::impassable;
-}
-
-constexpr inline void collision_move(const map_t& map, actor_t::direction dir)
-{
-  const enum actor_t::collision c = collision(map, state.player.world, dir);
-  state.player.move(c, dir);
-}
-
-void change_maps()
-{
-  const map_t& map = maps[state.map];
-
-#define _has(_dir_) (map.connections[map_t::connection_t::_dir_].map != map_t::unconnected)
-#define _get(_dir_) (maps[map.connections[map_t::connection_t::_dir_].map])
-#define _offset(_dir_) (map.connections[map_t::connection_t::_dir_].offset)
-
-  const block_t block = state.player.world.to_block();
-  if (block.y < 0) {
-    // north
-    if (_has(north)) {
-      const map_t& north_map = _get(north);
-      state.player.world.y = ((north_map.height + block.y) << 1) | (state.player.world.y & 1);
-      state.player.world.x = ((block.x - _offset(north)) << 1) | (state.player.world.x & 1);
-      state.map = map.connections[map_t::connection_t::north].map;
-    }
-  } else if (block.y >= static_cast<int32_t>(map.height)) {
-    // south
-    if (_has(south)) {
-      state.player.world.y = ((block.y - map.height) << 1) | (state.player.world.y & 1);
-      state.player.world.x = ((block.x - _offset(south)) << 1) | (state.player.world.x & 1);
-      state.map = map.connections[map_t::connection_t::south].map;
-    }
-  } else if (block.x < 0) {
-    // west
-    if (_has(west)) {
-      const map_t& west_map = _get(west);
-      state.player.world.x = ((west_map.width + block.x) << 1) | (state.player.world.x & 1);
-      state.player.world.y = ((block.y - _offset(west)) << 1) | (state.player.world.y & 1);
-      state.map = map.connections[map_t::connection_t::west].map;
-    }
-  } else if (block.x >= static_cast<int32_t>(map.width)) {
-    // east
-    if (_has(east)) {
-      state.player.world.x = ((block.x - map.width) << 1) | (state.player.world.x & 1);
-      state.player.world.y = ((block.y - _offset(east)) << 1) | (state.player.world.y & 1);
-      state.map = map.connections[map_t::connection_t::east].map;
-    }
-  }
-
-#undef _offset
-#undef _get
-#undef _has
-}
-
-constexpr inline bool is_outside(const enum map_t::map& map_id)
-{
-  const map_t& map = maps[map_id];
-  switch (map.tileset) {
-  case tileset_t::overworld: [[fallthrough]];
-  case tileset_t::plateau:
-    return true;
-  default:
-    return false;
-  }
-}
-
-struct collision_direction_t {
-  enum actor_t::collision collision;
-  enum actor_t::direction direction;
-};
-
-constexpr inline collision_direction_t find_direction(const map_t& map, const world_t& world, const enum actor_t::direction facing)
-{
-  // first, try `facing`, as this is typically correct in non- edge-cases
-  const enum actor_t::collision c_facing = collision(map, world, facing);
-  if (c_facing != actor_t::impassable)
-    return {c_facing, facing};
-
-  // otherwise try all other directions
-  // (this checks facing a second time for no reason)
-  constexpr enum actor_t::direction dirs[] = {actor_t::up, actor_t::down, actor_t::left, actor_t::right};
-  for (const enum actor_t::direction& dir : dirs) {
-    const enum actor_t::collision c = collision(map, world, dir);
-    if (c != actor_t::impassable)
-      return {c, dir};
-  }
-
-  return {actor_t::impassable, facing};
-}
-
-void update_warp()
-{
-  if (state.player.moving) return;
-  world_t& coord = state.player.world;
-
-  for (uint32_t j = 0; j < map_objects[state.map].warp_length; j++) {
-    const warp_event_t& warp = map_objects[state.map].warp_events[j];
-    if (coord.x == warp.position.x && coord.y == warp.position.y) {
-      if (warp.destination.map == map_t::last_map) {
-	if (state.last_map == map_t::last_map) {
-	  // use last_map as a sentinel value for "the player hasn't
-	  // warped yet". This should never happen in normal gameplay.
-	  continue;
-	}
-
-	state.map = state.last_map;
-      } else {
-	// Only change last_map if the current map is an "outside"
-	// map. Warps that use last_map are designed to be used this
-	// way.
-	if (is_outside(state.map)) state.last_map = state.map;
-
-	state.map = warp.destination.map;
-      }
-      // warp_index starts at 1
-      const warp_event_t& dest = map_objects[state.map].warp_events[warp.destination.warp_index - 1];
-      coord.x = dest.position.x;
-      coord.y = dest.position.y;
-
-      // force the player to move off of the warp
-
-      const collision_direction_t c_d = find_direction(maps[state.map], state.player.world, state.player.facing);
-      state.player.move(c_d.collision, c_d.direction);
-
-      // must return: because map state.map changed, the rest of this
-      // loop is invalid
-      return;
+      */
     }
   }
 }
 
-void check_sign()
-{
-  const world_t coord = direction_offset(state.player.world, state.player.facing);
-  const map_t& map = maps[state.map];
-  const object_t& obj = map_objects[state.map];
-
-  for (uint32_t i = 0; i < obj.bg_length; i++) {
-    const bg_event_t& event = obj.bg_events[i];
-    const bool position_match = event.position.x == coord.x && event.position.y == coord.y;
-    if (position_match && event.sign_id != 0xff) {
-      const start_size_t& text = map.text_pointers[event.sign_id];
-    }
-  }
-}
-
-static uint32_t stats_page = 1;
-static uint8_t level = 70;
-
 void update()
 {
-  state.player.tick();
-  change_maps();
-  update_warp();
+  //state.player.tick();
 
-  /*
-  if      (event::cursor_left() ) collision_move(maps[state.map], actor_t::left);
-  else if (event::cursor_right()) collision_move(maps[state.map], actor_t::right);
-  else if (event::cursor_up()   ) collision_move(maps[state.map], actor_t::up);
-  else if (event::cursor_down() ) collision_move(maps[state.map], actor_t::down);
-  else if (event::button_a()    ) check_sign();
-  */
+  enum window_t::input_event window_input_event;
 
-  if      (event::cursor_left() ) pokemon_raw_index = (pokemon_raw_index - 1);
-  else if (event::cursor_right()) pokemon_raw_index = (pokemon_raw_index + 1);
-  else if (event::cursor_up()   ) level++;
-  else if (event::cursor_down() ) level--;
-  else if (event::button_a()    ) stats_page = !stats_page;
-
-  if      (pokemon_raw_index < 0) pokemon_raw_index = pokemon_t::count - 1;
-  else if (pokemon_raw_index >= pokemon_t::count) pokemon_raw_index = 0;
+  if      (event::cursor_left() ) window_input_event = window_t::input_left;
+  else if (event::cursor_right()) window_input_event = window_t::input_right;
+  else if (event::cursor_up()   ) window_input_event = window_t::input_up;
+  else if (event::cursor_down() ) window_input_event = window_t::input_down;
+  else if (event::button_a() )    window_input_event = window_t::input_a;
+  else if (event::button_b() )    window_input_event = window_t::input_b;
+  else return;
 
+  state.player[0].window_stack.update(window_input_event,
+				      state.player[0].trainer);
 }
 
 static uint32_t frame = 0;
@@ -513,7 +291,7 @@ void render()
 {
   frame++;
 
-  const offset_t offset = state.player.offset();
+  const offset_t offset = state.player[0].actor.offset();
 
   render_sprites(offset);
 
@@ -524,33 +302,11 @@ void render()
   vdp2.reg.SCYIN0 = offset.y;
   vdp2.reg.SCYDN0 = 0;
 
-  render_map();
+  //render_map();
+  state.player[0].window_stack.draw(state.draw.base_pattern.font,
+				    state.player[0].trainer);
 
-  draw_menu(state.draw.base_pattern.font, fight_menu);
-  cursor_t cursor = { 1, 1 };
-  draw_menu_cursor(state.draw.base_pattern.font, fight_menu, cursor);
-
-  static pokemon_instance_t pokemon_instance;
-  pokemon_instance.species = static_cast<enum pokemon_t::pokemon>(pokemon_raw_index);
-  pokemon_instance.stat_experience = {0, 0, 0, 0, 0};
-  pokemon_instance.determinant_values.dvs = 0b1110'0101'1000'0110;
-  pokemon_instance.level = level;
-  pokemon_instance.determine_stats();
-  pokemon_instance.learn_all_moves();
-  if (frame % 4 == 0)
-    pokemon_instance.current_hit_points++;
-  if (pokemon_instance.current_hit_points > pokemon_instance.stat_values.hit_points)
-    pokemon_instance.current_hit_points = 0;
-
-  switch (stats_page) {
-  default:
-  case 0:
-    draw_stats1(state.draw.base_pattern.font, pokemon_instance);
-    break;
-  case 1:
-    draw_stats2(state.draw.base_pattern.font, pokemon_instance);
-    break;
-  }
+  vdp2.reg.BGON = BGON__N0ON | BGON__N0TPON | BGON__N1ON;
 }
 
 extern "C"
@@ -580,9 +336,9 @@ void v_blank_in_int()
 
   smpc.reg.IREG[0].val = INTBACK__IREG0__STATUS_DISABLE;
   smpc.reg.IREG[1].val = ( INTBACK__IREG1__PERIPHERAL_DATA_ENABLE
-                           | INTBACK__IREG1__PORT2_15BYTE
-                           | INTBACK__IREG1__PORT1_15BYTE
-                           );
+                         | INTBACK__IREG1__PORT2_15BYTE
+                         | INTBACK__IREG1__PORT1_15BYTE
+                         );
   smpc.reg.IREG[2].val = INTBACK__IREG2__MAGIC;
 
   smpc.reg.COMREG = COMREG__INTBACK;
@@ -700,12 +456,13 @@ void init_vdp2()
 
 void main()
 {
-  state.map = map_t::pallet_town;
+  //state.map = map_t::pallet_town;
   //state.map = map_t::pewter_gym;
   //state.map = map_t::viridian_forest;
   //state.map = map_t::route_2;
-  state.player.world.x = 6;
-  state.player.world.y = 6;
+  //state.player.world.x = 6;
+  //state.player.world.y = 6;
+  default_party(state.player[0].trainer.party);
 
   load_vram();
 
@@ -741,4 +498,9 @@ void main()
 
   scu.reg.IST = 0;
   scu.reg.IMS = ~(IMS__SMPC | IMS__V_BLANK_IN);
+
+  window_stack_t& window_stack = state.player[0].window_stack;
+  window_stack.ix = 0;
+  window_stack.stack[0].type = window_descriptor_t::fight;
+  window_stack.stack[0].window = { 0 };
 }
diff --git a/menu.cpp b/menu.cpp
deleted file mode 100644
index 3acb6b6..0000000
--- a/menu.cpp
+++ /dev/null
@@ -1,73 +0,0 @@
-#include "graphic.hpp"
-#include "menu.hpp"
-#include "control.hpp"
-
-#define POKE "\x94"
-#define TRAINER "\x92"
-#define PKMN "\x96"
-#define S(v) reinterpret_cast<const uint8_t *>(v)
-
-const menu_t start_menu = {
-  .top_left = {10, 0},
-  .bottom_right = {19, 15},
-  .width = 1,
-  .height = 7,
-  .h_advance = 0,
-  .v_advance = 2,
-
-  .items = (menu_item_t[]){
-    { S(POKE "DEX") },
-    { S(POKE "MON") },
-    { S("ITEM"    ) },
-    { S(TRAINER   ) },
-    { S("SAVE"    ) },
-    { S("OPTION"  ) },
-    { S("EXIT"    ) },
-  },
-};
-
-const menu_t fight_menu = {
-  .top_left = {8, 12},
-  .bottom_right = {19, 17},
-  .width = 2,
-  .height = 2,
-  .h_advance = 6,
-  .v_advance = 2,
-
-  .items = (menu_item_t[]) {
-    { S("FIGHT") }, { S(PKMN ) },
-    { S("ITEM" ) }, { S("RUN") },
-  },
-};
-
-#undef S
-
-void draw_menu(const uint32_t base_pattern,
-	       const menu_t& menu)
-{
-  draw_box_border(base_pattern,
-		  menu.top_left, menu.bottom_right);
-  draw_box_background(base_pattern,
-		      menu.top_left, menu.bottom_right);
-
-  for (uint32_t y = 0; y < menu.height; y++) {
-    for (uint32_t x = 0; x < menu.width; x++) {
-      const menu_item_t& item = menu.items[menu.width * y + x];
-
-      const uint32_t cell_x = menu.top_left.x + 2 + (menu.h_advance * x);
-      const uint32_t cell_y = menu.top_left.y + menu.v_advance + (menu.v_advance * y);
-
-      draw_text(base_pattern, item.label, cell_x, cell_y);
-    }
-  }
-}
-
-void draw_menu_cursor(const uint32_t base_pattern,
-		      const menu_t& menu,
-		      const cursor_t& cursor)
-{
-  const uint32_t cell_x = menu.top_left.x + 1 + (menu.h_advance * cursor.x);
-  const uint32_t cell_y = menu.top_left.y + menu.v_advance + (menu.v_advance * cursor.y);
-
-  put_char(base_pattern, cell_x, cell_y, interactive::l_arrow_solid);
-}
diff --git a/menu.hpp b/menu.hpp
deleted file mode 100644
index 92abc93..0000000
--- a/menu.hpp
+++ /dev/null
@@ -1,31 +0,0 @@
-#include "coordinates.hpp"
-
-struct menu_item_t {
-  const uint8_t * label;
-};
-
-struct menu_t {
-  screen_cell_t top_left; // in cells
-  screen_cell_t bottom_right; // in cells
-  uint8_t width; // in menu items
-  uint8_t height; // in menu items
-  uint8_t h_advance; // in cells
-  uint8_t v_advance; // in cells
-
-  const menu_item_t * items;
-};
-
-struct cursor_t {
-  uint16_t x; // in menu items
-  uint16_t y; // in menu items
-};
-
-extern const menu_t start_menu;
-extern const menu_t fight_menu;
-
-void draw_menu(const uint32_t base_pattern,
-	       const menu_t& menu);
-
-void draw_menu_cursor(const uint32_t base_pattern,
-		      const menu_t& menu,
-		      const cursor_t& cursor);
diff --git a/overworld/overworld.cpp b/overworld/overworld.cpp
new file mode 100644
index 0000000..c207ed6
--- /dev/null
+++ b/overworld/overworld.cpp
@@ -0,0 +1,205 @@
+void overworld_update()
+{
+  change_maps();
+  update_warp();
+}
+
+constexpr inline world_t direction_offset(const world_t& world, const enum actor_t::direction dir)
+{
+  switch (dir) {
+  default: [[fallthrough]];
+  case actor_t::up:    return {world.x    , world.y - 1};
+  case actor_t::down:  return {world.x    , world.y + 1};
+  case actor_t::left:  return {world.x - 1, world.y    };
+  case actor_t::right: return {world.x + 1, world.y    };
+  }
+}
+
+constexpr inline uint8_t get_tile_ix(const map_t& map, const world_t& coord)
+{
+  // keep this synchronized with render_screen()
+
+  const uint8_t block_ix = get_block(map, coord.to_block());
+  const tileset_t& tileset = tilesets[map.tileset];
+  const uint8_t * block_start = &(tileset.blockset.start)[block_ix * 4 * 4];
+  const int32_t quadrant_x = 2 * (coord.x & 1);
+  const int32_t quadrant_y = 2 * (coord.y & 1);
+
+  const int32_t block_row = 4 * (quadrant_y + 1);
+  const uint8_t tile_ix = block_start[block_row + quadrant_x];
+
+  return tile_ix;
+}
+
+constexpr inline enum actor_t::collision collision(const map_t& map,
+						   const world_t& world,
+						   enum actor_t::direction direction)
+{
+  const world_t coord = direction_offset(world, direction);
+  uint8_t collision_tile_ix = get_tile_ix(map, coord);
+
+  const tileset_t& tileset = tilesets[map.tileset];
+  for (uint32_t i = 0; i < tileset.collision.size; i++) {
+    if (tileset.collision.start[i] == collision_tile_ix)
+      return actor_t::passable;
+  }
+
+  // check ledge_tile pairs
+
+  uint8_t actor_tile_ix = get_tile_ix(map, world);
+
+  for (uint32_t i = 0; i < ledge_tiles_length; i++) {
+    const ledge_tile_t& lt = ledge_tiles[i];
+    if (direction == lt.direction
+	&& actor_tile_ix == lt.actor
+	&& collision_tile_ix == lt.collision) {
+      return actor_t::jump;
+    }
+  }
+
+  return actor_t::impassable;
+}
+
+constexpr inline void collision_move(const map_t& map, actor_t::direction dir)
+{
+  const enum actor_t::collision c = collision(map, state.player.world, dir);
+  state.player.move(c, dir);
+}
+
+void change_maps()
+{
+  const map_t& map = maps[state.map];
+
+#define _has(_dir_) (map.connections[map_t::connection_t::_dir_].map != map_t::unconnected)
+#define _get(_dir_) (maps[map.connections[map_t::connection_t::_dir_].map])
+#define _offset(_dir_) (map.connections[map_t::connection_t::_dir_].offset)
+
+  const block_t block = state.player.world.to_block();
+  if (block.y < 0) {
+    // north
+    if (_has(north)) {
+      const map_t& north_map = _get(north);
+      state.player.world.y = ((north_map.height + block.y) << 1) | (state.player.world.y & 1);
+      state.player.world.x = ((block.x - _offset(north)) << 1) | (state.player.world.x & 1);
+      state.map = map.connections[map_t::connection_t::north].map;
+    }
+  } else if (block.y >= static_cast<int32_t>(map.height)) {
+    // south
+    if (_has(south)) {
+      state.player.world.y = ((block.y - map.height) << 1) | (state.player.world.y & 1);
+      state.player.world.x = ((block.x - _offset(south)) << 1) | (state.player.world.x & 1);
+      state.map = map.connections[map_t::connection_t::south].map;
+    }
+  } else if (block.x < 0) {
+    // west
+    if (_has(west)) {
+      const map_t& west_map = _get(west);
+      state.player.world.x = ((west_map.width + block.x) << 1) | (state.player.world.x & 1);
+      state.player.world.y = ((block.y - _offset(west)) << 1) | (state.player.world.y & 1);
+      state.map = map.connections[map_t::connection_t::west].map;
+    }
+  } else if (block.x >= static_cast<int32_t>(map.width)) {
+    // east
+    if (_has(east)) {
+      state.player.world.x = ((block.x - map.width) << 1) | (state.player.world.x & 1);
+      state.player.world.y = ((block.y - _offset(east)) << 1) | (state.player.world.y & 1);
+      state.map = map.connections[map_t::connection_t::east].map;
+    }
+  }
+
+#undef _offset
+#undef _get
+#undef _has
+}
+
+struct collision_direction_t {
+  enum actor_t::collision collision;
+  enum actor_t::direction direction;
+};
+
+void check_sign()
+{
+  const world_t coord = direction_offset(state.player.world, state.player.facing);
+  const map_t& map = maps[state.map];
+  const object_t& obj = map_objects[state.map];
+
+  for (uint32_t i = 0; i < obj.bg_length; i++) {
+    const bg_event_t& event = obj.bg_events[i];
+    const bool position_match = event.position.x == coord.x && event.position.y == coord.y;
+    if (position_match && event.sign_id != 0xff) {
+      const start_size_t& text = map.text_pointers[event.sign_id];
+    }
+  }
+}
+
+void update_warp()
+{
+  if (state.player.moving) return;
+  world_t& coord = state.player.world;
+
+  for (uint32_t j = 0; j < map_objects[state.map].warp_length; j++) {
+    const warp_event_t& warp = map_objects[state.map].warp_events[j];
+    if (coord.x == warp.position.x && coord.y == warp.position.y) {
+      if (warp.destination.map == map_t::last_map) {
+	if (state.last_map == map_t::last_map) {
+	  // use last_map as a sentinel value for "the player hasn't
+	  // warped yet". This should never happen in normal gameplay.
+	  continue;
+	}
+
+	state.map = state.last_map;
+      } else {
+	// Only change last_map if the current map is an "outside"
+	// map. Warps that use last_map are designed to be used this
+	// way.
+	if (is_outside(state.map)) state.last_map = state.map;
+
+	state.map = warp.destination.map;
+      }
+      // warp_index starts at 1
+      const warp_event_t& dest = map_objects[state.map].warp_events[warp.destination.warp_index - 1];
+      coord.x = dest.position.x;
+      coord.y = dest.position.y;
+
+      // force the player to move off of the warp
+
+      const collision_direction_t c_d = find_direction(maps[state.map], state.player.world, state.player.facing);
+      state.player.move(c_d.collision, c_d.direction);
+
+      // must return: because map state.map changed, the rest of this
+      // loop is invalid
+      return;
+    }
+  }
+}
+
+constexpr inline collision_direction_t find_direction(const map_t& map, const world_t& world, const enum actor_t::direction facing)
+{
+  // first, try `facing`, as this is typically correct in non- edge-cases
+  const enum actor_t::collision c_facing = collision(map, world, facing);
+  if (c_facing != actor_t::impassable)
+    return {c_facing, facing};
+
+  // otherwise try all other directions
+  // (this checks facing a second time for no reason)
+  constexpr enum actor_t::direction dirs[] = {actor_t::up, actor_t::down, actor_t::left, actor_t::right};
+  for (const enum actor_t::direction& dir : dirs) {
+    const enum actor_t::collision c = collision(map, world, dir);
+    if (c != actor_t::impassable)
+      return {c, dir};
+  }
+
+  return {actor_t::impassable, facing};
+}
+
+constexpr inline bool is_outside(const enum map_t::map& map_id)
+{
+  const map_t& map = maps[map_id];
+  switch (map.tileset) {
+  case tileset_t::overworld: [[fallthrough]];
+  case tileset_t::plateau:
+    return true;
+  default:
+    return false;
+  }
+}
diff --git a/render_map.hpp b/overworld/render_map.hpp
similarity index 95%
rename from render_map.hpp
rename to overworld/render_map.hpp
index 28ab3c1..4b61e33 100644
--- a/render_map.hpp
+++ b/overworld/render_map.hpp
@@ -59,12 +59,6 @@ constexpr inline uint8_t get_block(const map_t& map, block_t block)
 #undef _has
 }
 
-struct cell_offset
-{
-  static constexpr int32_t x = (320 - 160) / (2 * 8);
-  static constexpr int32_t y = (240 - 144) / (2 * 8);
-};
-
 static inline void render_screen(const uint32_t base_pattern,
 				 const map_t& map,
 				 const world_t& origin,
diff --git a/party.cpp b/party.cpp
new file mode 100644
index 0000000..45baa6e
--- /dev/null
+++ b/party.cpp
@@ -0,0 +1,9 @@
+#include "party.hpp"
+
+#include "pokemon.hpp"
+
+void default_party(party_t& party)
+{
+  party.size = 1;
+  party.pokemon_instances[0].init(pokemon_t::pikachu, 60);
+}
diff --git a/party.hpp b/party.hpp
new file mode 100644
index 0000000..df95b68
--- /dev/null
+++ b/party.hpp
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cstdint>
+
+#include "pokemon_instance.hpp"
+
+struct party_t {
+  static constexpr uint8_t max_size = 6;
+
+  pokemon_instance_t pokemon_instances[max_size];
+  uint8_t active_ix;
+  uint8_t size;
+
+  const pokemon_instance_t& active_pokemon() const
+  {
+    return pokemon_instances[active_ix];
+  }
+};
+
+void default_party(party_t& party);
diff --git a/player.hpp b/player.hpp
new file mode 100644
index 0000000..2993f57
--- /dev/null
+++ b/player.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "gen/maps.hpp"
+#include "actor.hpp"
+#include "trainer.hpp"
+#include "window/window_stack.hpp"
+
+struct player_state_t {
+  enum map_t::map map;
+  enum map_t::map last_map;
+  window_stack_t window_stack;
+  actor_t actor;
+  trainer_state_t trainer;
+};
diff --git a/pokemon_instance.cpp b/pokemon_instance.cpp
index 13086b2..2c0e264 100644
--- a/pokemon_instance.cpp
+++ b/pokemon_instance.cpp
@@ -97,3 +97,19 @@ void pokemon_instance_t::learn_all_moves()
       break;
   }
 }
+
+void
+pokemon_instance_t::init(const enum pokemon_t::pokemon species,
+			 const uint8_t level)
+{
+  this->species = species;
+  this->level = level;
+
+  stat_experience = {0, 0, 0, 0, 0};
+  determinant_values.dvs = 0b1110'0101'1000'0110;
+  determine_stats();
+  learn_all_moves();
+  current_hit_points = stat_values.hit_points;
+  total_experience = 0; // fixme exp
+  ailment = ailment_t::ok;
+}
diff --git a/pokemon_instance.hpp b/pokemon_instance.hpp
index 39b9c34..6ddee6b 100644
--- a/pokemon_instance.hpp
+++ b/pokemon_instance.hpp
@@ -70,6 +70,8 @@ struct move_instance_t {
 };
 
 struct pokemon_instance_t {
+  static constexpr uint8_t maximum_moves = 4;
+
   uint8_t nickname[12];
   enum pokemon_t::pokemon species;
   uint8_t level;
@@ -77,7 +79,7 @@ struct pokemon_instance_t {
   determinant_values_t determinant_values;
   stat_values_t stat_values;
   stat_experience_t stat_experience;
-  move_instance_t move_instances[4];
+  move_instance_t move_instances[maximum_moves];
   uint16_t current_hit_points;
   enum ailment_t::ailment ailment;
 
@@ -86,8 +88,19 @@ struct pokemon_instance_t {
   // - id number
   // - original trainer
 
+  inline constexpr uint8_t moves_count() const
+  {
+    for (int32_t i = maximum_moves; i > 0; i--) {
+      if (move_instances[i - 1].type != move_t::no_move)
+	return i;
+    }
+    return 0;
+  }
+
   void determine_stats();
 
   void learn_move(enum move_t::move move, int32_t index);
   void learn_all_moves();
+  void init(const enum pokemon_t::pokemon species,
+	    const uint8_t level);
 };
diff --git a/stats.cpp b/stats.cpp
new file mode 100644
index 0000000..278cb12
--- /dev/null
+++ b/stats.cpp
@@ -0,0 +1,31 @@
+  draw_menu(state.draw.base_pattern.font, fight_menu);
+  cursor_t cursor = { 1, 1 };
+  draw_menu_cursor(state.draw.base_pattern.font, fight_menu, cursor);
+
+  static pokemon_instance_t pokemon_instance;
+  if (frame % 4 == 0)
+    pokemon_instance.current_hit_points++;
+  if (pokemon_instance.current_hit_points > pokemon_instance.stat_values.hit_points)
+    pokemon_instance.current_hit_points = 0;
+
+  switch (stats_page) {
+  default:
+  case 0:
+    draw_stats1(state.draw.base_pattern.font, pokemon_instance);
+    break;
+  case 1:
+    draw_stats2(state.draw.base_pattern.font, pokemon_instance);
+    break;
+  }
+
+
+  if      (event::cursor_left() ) pokemon_raw_index = (pokemon_raw_index - 1);
+  else if (event::cursor_right()) pokemon_raw_index = (pokemon_raw_index + 1);
+  else if (event::cursor_up()   ) level++;
+  else if (event::cursor_down() ) level--;
+  else if (event::button_a()    ) stats_page = !stats_page;
+
+  if      (pokemon_raw_index < 0) pokemon_raw_index = pokemon_t::count - 1;
+  else if (pokemon_raw_index >= pokemon_t::count) pokemon_raw_index = 0;
+
+}
diff --git a/tools/generate/pokemon/moves.py b/tools/generate/pokemon/moves.py
index dd9e29d..a095186 100644
--- a/tools/generate/pokemon/moves.py
+++ b/tools/generate/pokemon/moves.py
@@ -84,7 +84,7 @@ def move(constant_index, constant_name):
             ".animation = 0,",
             ".effect = 0,",
             f".power = {_move.power},",
-            ".type = 0,",
+            f".type = type_t::{_move.type.removesuffix('_TYPE').lower()},",
             f".accuracy = {_move.accuracy},",
             f".pp = {_move.pp},",
         "},"
@@ -104,6 +104,7 @@ def includes_source():
     yield '#include <cstdint>'
     yield ''
     yield '#include "moves.hpp"'
+    yield '#include "types.hpp"'
     yield ''
 
 def generate_source():
diff --git a/trainer.hpp b/trainer.hpp
new file mode 100644
index 0000000..5fd0d38
--- /dev/null
+++ b/trainer.hpp
@@ -0,0 +1,8 @@
+#pragma once
+
+#include "party.hpp"
+
+struct trainer_state_t {
+  party_t party;
+  // items
+};
diff --git a/menu/dialog.cpp b/window/dialog.cpp
similarity index 100%
rename from menu/dialog.cpp
rename to window/dialog.cpp
diff --git a/window/menu.cpp b/window/menu.cpp
new file mode 100644
index 0000000..de96856
--- /dev/null
+++ b/window/menu.cpp
@@ -0,0 +1,306 @@
+#include "menu.hpp"
+#include "window.hpp"
+#include "../graphic.hpp"
+#include "../control.hpp"
+#include "../trainer.hpp"
+#include "../font.hpp"
+#include "../number.hpp"
+#include "../gen/pokemon/moves.hpp"
+#include "../gen/pokemon/types.hpp"
+
+#define POKE "\x94"
+#define TRAINER "\x92"
+#define PKMN "\x96"
+
+#define S(v) reinterpret_cast<const uint8_t *>(v)
+
+static void draw_cursor(const uint32_t base_pattern,
+			const menu_t& menu,
+			const cursor_t& cursor)
+{
+  const uint32_t cell_x = menu.top_left.x + 1 + (menu.h_advance * cursor.x);
+  const uint32_t cell_y = menu.top_left.y + menu.v_advance + (menu.v_advance * cursor.y);
+
+  put_char(base_pattern, cell_x, cell_y, interactive::l_arrow_solid);
+}
+
+static void draw_menu(const uint32_t base_pattern,
+		      const menu_t& menu,
+		      const trainer_state_t& trainer_state)
+{
+  draw_box_border(base_pattern,
+		  menu.top_left, menu.bottom_right);
+  draw_box_background(base_pattern,
+		      menu.top_left, menu.bottom_right);
+
+  for (uint32_t y = 0; y < menu.height; y++) {
+    for (uint32_t x = 0; x < menu.width; x++) {
+      const uint32_t cell_x = menu.top_left.x + 2 + (menu.h_advance * x);
+      const uint32_t cell_y = menu.top_left.y + menu.v_advance + (menu.v_advance * y);
+      const uint32_t menu_entry_index = menu.width * y + x;
+      const menu_entry_t& entry = menu.entry;
+
+      if (menu.entry_type == menu_t::labels) {
+	draw_text(base_pattern,
+		  entry.labels[menu_entry_index],
+		  cell_x, cell_y);
+      } else {
+	draw_text(base_pattern,
+		  entry.label_func(menu_entry_index, trainer_state),
+		  cell_x, cell_y);
+      }
+    }
+  }
+}
+
+void
+window__menu_t::draw(const uint32_t base_pattern,
+		     const union window_descriptor_t::data& data,
+		     const window_t& window,
+		     const trainer_state_t& trainer_state)
+{
+  const menu_t& menu = *data.menu;
+  draw_menu(base_pattern, menu, trainer_state);
+  draw_cursor(base_pattern, menu, window.cursor);
+}
+
+static void
+_draw_move_types(const uint32_t base_pattern,
+		 const uint8_t index,
+		 const trainer_state_t& trainer_state)
+{
+  // this is fully custom, not worth making a data model for this
+
+  constexpr screen_cell_t top_left = {0, 8};
+  constexpr screen_cell_t bottom_right = {10, 12};
+
+  draw_box_border(base_pattern, top_left, bottom_right);
+  draw_box_background(base_pattern,
+		      top_left, bottom_right);
+
+  const pokemon_instance_t& pokemon_instance = trainer_state.party.active_pokemon();
+  const move_instance_t& move_instance = pokemon_instance.move_instances[index];
+  const move_t& move = moves[move_instance.type];
+
+  draw_text(base_pattern,
+	    S("TYPE/"),
+	    top_left.x + 1, top_left.y + 1);
+
+  draw_text(base_pattern,
+	    types[move.type].name,
+	    top_left.x + 2, top_left.y + 2);
+
+  draw_number_right_align(base_pattern,
+			  {top_left.x + 5, top_left.y + 3},
+			  move_instance.pp,
+			  2,
+			  ascii_to_font(' '));
+
+  put_char(base_pattern,
+	   top_left.x + 7, top_left.y + 3,
+	   ascii_to_font('/'));
+
+  draw_number_right_align(base_pattern,
+			  {top_left.x + 8, top_left.y + 3},
+			  move.pp,
+			  2,
+			  ascii_to_font(' '));
+}
+
+void
+window__menu_t::draw_fight_moves(const uint32_t base_pattern,
+				 const union window_descriptor_t::data& data,
+				 const window_t& window,
+				 const trainer_state_t& trainer_state)
+{
+  window__menu_t::draw(base_pattern,
+		       data,
+		       window,
+		       trainer_state);
+
+  const menu_t& menu = *data.menu;
+  const cursor_t& cursor = window.cursor;
+  const uint32_t menu_entry_index = menu.width * cursor.y + cursor.x;
+
+  _draw_move_types(base_pattern,
+		   menu_entry_index,
+		   trainer_state);
+}
+
+static inline constexpr void
+_move_cursor(const uint8_t width,
+	     const uint8_t height,
+	     const enum window_t::input_event event,
+	     cursor_t& cursor)
+{
+  switch (event) {
+  case window_t::input_left:
+    if ((--cursor.x) < 0) cursor.x = width - 1;
+    break;
+  case window_t::input_right:
+    if ((++cursor.x) >= width) cursor.x = 0;
+    break;
+  case window_t::input_up:
+    if ((--cursor.y) < 0) cursor.y = height - 1;
+    break;
+  case window_t::input_down:
+    if ((++cursor.y) >= height) cursor.y = 0;
+    break;
+  default: break;
+  }
+}
+
+window_descriptor_t::result
+window__menu_t::update(const union window_descriptor_t::data& data,
+		       window_t& window,
+		       trainer_state_t& trainer_state,
+		       const enum window_t::input_event event)
+{
+  const menu_t& menu = *data.menu;
+
+  switch (event) {
+  case window_t::input_left: [[fallthrough]];
+  case window_t::input_right: [[fallthrough]];
+  case window_t::input_up: [[fallthrough]];
+  case window_t::input_down:
+    _move_cursor(menu.width, menu.height, event, window.cursor);
+    break;
+
+  case window_t::input_a: break;
+  case window_t::input_b: break;
+  default: break;
+  }
+
+  return { window_t::no_op };
+}
+
+window_descriptor_t::result
+window__menu_t::update_fight(const union window_descriptor_t::data& data,
+			     window_t& window,
+			     trainer_state_t& trainer_state,
+			     const enum window_t::input_event event)
+{
+  const menu_t& menu = *data.menu;
+
+  switch (event) {
+  case window_t::input_a:
+    {
+      const cursor_t& cursor = window.cursor;
+      const uint32_t menu_entry_index = menu.width * cursor.y + cursor.x;
+      switch (menu_entry_index) {
+      case 0: // FIGHT
+	return { window_t::spawn, window_descriptor_t::fight_moves };
+	break;
+      case 1: // PKMN
+	break;
+      case 2: // ITEM
+	break;
+      case 3: // RUN
+	break;
+      default:
+	break;
+      }
+    }
+    break;
+  case window_t::input_b:
+    break;
+  default:
+    _move_cursor(menu.width, menu.width, event, window.cursor);
+    break;
+  }
+
+  return { window_t::no_op };
+}
+
+static uint8_t const * const
+_get_move_string(const uint32_t index,
+		 const trainer_state_t& trainer_state)
+{
+  const pokemon_instance_t& pokemon_instance = trainer_state.party.active_pokemon();
+
+  if (index >= pokemon_instance_t::maximum_moves ||
+      pokemon_instance.move_instances[index].type == move_t::no_move)
+    return S("-");
+  else {
+    return moves[pokemon_instance.move_instances[index].type].name;
+  }
+}
+
+
+window_descriptor_t::result
+window__menu_t::update_fight_moves(const union window_descriptor_t::data& data,
+				   window_t& window,
+				   trainer_state_t& trainer_state,
+				   const enum window_t::input_event event)
+{
+  const menu_t& menu = *data.menu;
+  const uint8_t max_height = trainer_state.party.active_pokemon().moves_count();
+
+  switch (event) {
+  case window_t::input_a:
+    break;
+  case window_t::input_b:
+    return { window_t::dismiss };
+    break;
+  default:
+    _move_cursor(menu.width, max_height, event, window.cursor);
+    break;
+  }
+
+  return { window_t::no_op };
+}
+
+const menu_t menu_fight_moves = {
+  .top_left = {4, 12},
+  .bottom_right = {19, 17},
+  .width = 1,
+  .height = 4,
+  .h_advance = 0,
+  .v_advance = 1,
+
+  .entry_type = menu_t::func,
+  .entry = {
+    { .label_func = _get_move_string }
+  }
+};
+
+const menu_t menu_start = {
+  .top_left = {10, 0},
+  .bottom_right = {19, 15},
+  .width = 1,
+  .height = 7,
+  .h_advance = 0,
+  .v_advance = 2,
+
+  .entry_type = menu_t::labels,
+  .entry {
+    .labels = (menu_label_t[]){
+      { S(POKE "DEX") },
+      { S(POKE "MON") },
+      { S("ITEM"    ) },
+      { S(TRAINER   ) },
+      { S("SAVE"    ) },
+      { S("OPTION"  ) },
+      { S("EXIT"    ) },
+    },
+  }
+};
+
+const menu_t menu_fight = {
+  .top_left = {8, 12},
+  .bottom_right = {19, 17},
+  .width = 2,
+  .height = 2,
+  .h_advance = 6,
+  .v_advance = 2,
+
+  .entry_type = menu_t::labels,
+  .entry = {
+    .labels = (menu_label_t[]) {
+      { S("FIGHT") }, { S(PKMN ) },
+      { S("ITEM" ) }, { S("RUN") },
+    }
+  },
+};
+
+#undef S
diff --git a/window/menu.hpp b/window/menu.hpp
new file mode 100644
index 0000000..7078c5d
--- /dev/null
+++ b/window/menu.hpp
@@ -0,0 +1,35 @@
+#pragma once
+
+#include "../coordinates.hpp"
+#include "../trainer.hpp"
+
+typedef uint8_t const * const menu_label_t;
+
+struct menu_entry_t {
+  union {
+    menu_label_t * labels;
+    menu_label_t (* const label_func)(const uint32_t index,
+				      const trainer_state_t& trainer);
+  };
+};
+
+struct menu_t {
+  enum entry_type {
+    labels,
+    func,
+  };
+
+  const screen_cell_t top_left; // in cells
+  const screen_cell_t bottom_right; // in cells
+  const uint8_t width; // in menu items
+  const uint8_t height; // in menu items
+  const uint8_t h_advance; // in cells
+  const uint8_t v_advance; // in cells
+
+  const enum entry_type entry_type;
+  const menu_entry_t entry;
+};
+
+extern const menu_t menu_start;
+extern const menu_t menu_fight;
+extern const menu_t menu_fight_moves;
diff --git a/menu/stats.cpp b/window/stats.cpp
similarity index 100%
rename from menu/stats.cpp
rename to window/stats.cpp
diff --git a/menu/stats.hpp b/window/stats.hpp
similarity index 100%
rename from menu/stats.hpp
rename to window/stats.hpp
diff --git a/window/window.cpp b/window/window.cpp
new file mode 100644
index 0000000..0f75069
--- /dev/null
+++ b/window/window.cpp
@@ -0,0 +1,21 @@
+#include "window.hpp"
+
+#include "menu.hpp"
+
+const window_descriptor_t window_descriptors[] = {
+  [window_descriptor_t::start] = {
+    .data = { .menu = &menu_start },
+    .draw = window__menu_t::draw,
+    .update = window__menu_t::update,
+  },
+  [window_descriptor_t::fight] = {
+    .data = { .menu = &menu_fight },
+    .draw = window__menu_t::draw,
+    .update = window__menu_t::update_fight,
+  },
+  [window_descriptor_t::fight_moves] = {
+    .data = { .menu = &menu_fight_moves },
+    .draw = window__menu_t::draw_fight_moves,
+    .update = window__menu_t::update_fight_moves,
+  },
+};
diff --git a/window/window.hpp b/window/window.hpp
new file mode 100644
index 0000000..27a3eaa
--- /dev/null
+++ b/window/window.hpp
@@ -0,0 +1,113 @@
+#pragma once
+
+#include <cstdint>
+
+#include "menu.hpp"
+#include "../trainer.hpp"
+
+struct cursor_t {
+  int16_t x; // in menu items
+  int16_t y; // in menu items
+};
+
+struct window_t {
+  enum input_event {
+    input_up,
+    input_down,
+    input_left,
+    input_right,
+    input_a,
+    input_b,
+  };
+
+  enum window_event {
+    no_op,
+    spawn,
+    dismiss,
+  };
+
+  cursor_t cursor;
+};
+
+struct window_descriptor_t {
+  enum type {
+    start,
+    fight,
+    fight_moves,
+  };
+
+  union data {
+    menu_t const * const menu;
+  };
+
+  union data data;
+
+  struct result {
+    enum window_t::window_event window_event;
+    union {
+      uint8_t no_op;
+      enum type type;
+    };
+
+    result(enum window_t::window_event window_event,
+	   enum type type)
+      : window_event(window_event), type(type)
+    {}
+
+    result(enum window_t::window_event window_event)
+      : window_event(window_event), no_op(0)
+    {}
+  };
+
+  void
+  (* const draw)(const uint32_t base_pattern,
+		 const union data& data,
+		 const window_t& window,
+		 const trainer_state_t& trainer_state);
+
+  result
+  (* const update)(const union data& data,
+		   window_t& window,
+		   trainer_state_t& trainer_state,
+		   const enum window_t::input_event event
+		   );
+};
+
+extern const window_descriptor_t window_descriptors[];
+
+// window types
+
+struct window__menu_t {
+  static void
+  draw(const uint32_t base_pattern,
+       const union window_descriptor_t::data& data,
+       const window_t& window,
+       const trainer_state_t& trainer_state);
+
+  static void
+  draw_fight_moves(const uint32_t base_pattern,
+		   const union window_descriptor_t::data& data,
+		   const window_t& window,
+		   const trainer_state_t& trainer_state);
+
+  static window_descriptor_t::result
+  update(const union window_descriptor_t::data& data,
+	 window_t& window,
+	 trainer_state_t& trainer_state,
+	 const enum window_t::input_event event
+	 );
+
+  static window_descriptor_t::result
+  update_fight(const union window_descriptor_t::data& data,
+	       window_t& window,
+	       trainer_state_t& trainer_state,
+	       const enum window_t::input_event event
+	       );
+
+  static window_descriptor_t::result
+  update_fight_moves(const union window_descriptor_t::data& data,
+		     window_t& window,
+		     trainer_state_t& trainer_state,
+		     const enum window_t::input_event event
+		     );
+};
diff --git a/window/window_stack.hpp b/window/window_stack.hpp
new file mode 100644
index 0000000..d5a0d6d
--- /dev/null
+++ b/window/window_stack.hpp
@@ -0,0 +1,67 @@
+#pragma once
+
+#include <cstdint>
+
+#include "window.hpp"
+#include "../trainer.hpp"
+
+struct window_stack_t {
+  struct {
+    enum window_descriptor_t::type type;
+    window_t window;
+  } stack[16];
+  int8_t ix;
+
+  constexpr inline void
+  draw(const uint32_t base_pattern,
+       trainer_state_t& trainer_state);
+
+  constexpr inline void
+  update(const enum window_t::input_event event,
+	 trainer_state_t& trainer_state);
+};
+
+constexpr inline void
+window_stack_t::draw(const uint32_t base_pattern,
+		     trainer_state_t& trainer_state)
+{
+  if (ix < 0) return;
+
+  const window_descriptor_t& descriptor = \
+    window_descriptors[stack[ix].type];
+
+  descriptor.draw(base_pattern,
+		  descriptor.data,
+		  stack[ix].window,
+		  trainer_state);
+}
+
+constexpr inline void
+window_stack_t::update(const enum window_t::input_event event,
+		       trainer_state_t& trainer_state)
+{
+  if (ix < 0) return;
+
+  const window_descriptor_t& descriptor = \
+    window_descriptors[stack[ix].type];
+
+  const window_descriptor_t::result& result = \
+    descriptor.update(descriptor.data,
+		      stack[ix].window,
+		      trainer_state,
+		      event);
+
+  switch (result.window_event) {
+  case window_t::spawn:
+    if (ix >= 15) return;
+    ix++;
+    stack[ix].type = result.type;
+    stack[ix].window.cursor = { 0 };
+    break;
+  case window_t::dismiss:
+    if (ix < 0) return;
+    ix--;
+  default:
+    break;
+  }
+}