diff --git a/CMakeLists.txt b/CMakeLists.txt
index 80b750c..cf3f26d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,6 +11,7 @@ find_package(Gint 2.1 REQUIRED)
 
 set(SOURCES
   src/main.c
+  src/engine.c
   # ...
 )
 # Shared assets, fx-9860G-only assets and fx-CG-50-only assets
@@ -20,6 +21,7 @@ set(ASSETS
 set(ASSETS_fx
   assets-fx/levels.png
   assets-fx/title.png
+  assets-fx/spritesheet.png
   assets-fx/font_mystere.png
   # ...
 )
diff --git a/MystNB.g1a b/MystNB.g1a
index 43edcef..c7d3956 100644
Binary files a/MystNB.g1a and b/MystNB.g1a differ
diff --git a/assets-fx/fxconv-metadata.txt b/assets-fx/fxconv-metadata.txt
index 961995f..3a685d7 100644
--- a/assets-fx/fxconv-metadata.txt
+++ b/assets-fx/fxconv-metadata.txt
@@ -1,10 +1,6 @@
-levels.png:
+*.png:
   type: bopti-image
-  name: img_levels
-
-title.png:
-  type: bopti-image
-  name: img_title
+  name_regex: (.*)\.png img_\1
 
 font_mystere.png:
   type: font
diff --git a/assets-fx/spritesheet.png b/assets-fx/spritesheet.png
new file mode 100644
index 0000000..3bbfcd1
Binary files /dev/null and b/assets-fx/spritesheet.png differ
diff --git a/src/engine.c b/src/engine.c
new file mode 100644
index 0000000..d5fe81d
--- /dev/null
+++ b/src/engine.c
@@ -0,0 +1,56 @@
+#include <gint/display.h>
+#include <gint/keyboard.h>
+#include "engine.h"
+
+#define CELL_X(x) (-2 + 10 * (x))
+#define CELL_Y(y) (-3 + 10 * (y))
+
+//---
+//  Rendering
+//---
+
+static void engine_draw_player(struct player const *player)
+{
+	extern bopti_image_t img_spritesheet;
+
+	dsubimage(CELL_X(player->x) - 1, CELL_Y(player->y) - 5,
+		&img_spritesheet, player->dir * 12, 0, 12, 16, DIMAGE_NONE);
+}
+
+void engine_draw(struct game const *game)
+{
+	dclear(C_WHITE);
+
+	for(int p = 0; game->players[p]; p++)
+	{
+		engine_draw_player(game->players[p]);
+	}
+}
+
+//---
+//  Physics
+//---
+
+/* Check whether a cell of the map is walkable */
+static int map_walkable(struct map const *map, int x, int y)
+{
+	/* TODO: Read the map's data array */
+	return (x >= 1) && (y >= 1) && (x < map->w - 1) && (y < map->h - 1);
+}
+
+int engine_move(struct game *game, struct player *player, int dir)
+{
+	int dx = (dir == DIR_RIGHT) - (dir == DIR_LEFT);
+	int dy = (dir == DIR_DOWN)  - (dir == DIR_UP);
+
+	/* Always update the direction */
+	player->dir = dir;
+
+	/* Only move the player if the destination is walkable */
+	if(!map_walkable(game->map, player->x + dx, player->y + dy)) return 0;
+
+	player->x += dx;
+	player->y += dy;
+
+	return 1;
+}
diff --git a/src/engine.h b/src/engine.h
new file mode 100644
index 0000000..2dc81bf
--- /dev/null
+++ b/src/engine.h
@@ -0,0 +1,55 @@
+#ifndef _MYSTNB_ENGINE_H
+#define _MYSTNB_ENGINE_H
+
+#include <stdint.h>
+
+#define PLAYER_COUNT 1
+
+/* Directions */
+#define DIR_DOWN   0
+#define DIR_RIGHT  1
+#define DIR_UP     2
+#define DIR_LEFT   3
+
+/* struct player: A player on the map, triggering actions as they move */
+struct player
+{
+	/* Position in map */
+	int x, y;
+	/* Direction currently facing */
+	int dir;
+	/* Animation and frame */
+	struct animation const *anim;
+	int frame;
+};
+
+/* struct map: A map with moving doors, collectibles, and fog */
+struct map
+{
+	/* Width and height */
+	int w, h;
+	/* Whether fog is enabled */
+	int fog;
+	/* Raw data */
+	uint8_t *data;
+};
+
+/* struct game: A running game with a map and some players */
+struct game
+{
+	/* Current map */
+	struct map *map;
+	/* Players */
+	struct player *players[PLAYER_COUNT + 1];
+	/* Current game time (ms) */
+	int time;
+};
+
+/* Draw the current game frame from scratch; does not dupdate() */
+void engine_draw(struct game const *game);
+
+/* Try to move a player along a direction. Returns 1 if the move is successful,
+   0 otherwise (collisions or out-of-bounds moves) */
+int engine_move(struct game *game, struct player *player, int direction);
+
+#endif /* _MYSTNB_ENGINE_H */
diff --git a/src/main.c b/src/main.c
index 0a72769..19f21d4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,6 +1,8 @@
 #include <gint/display.h>
 #include <gint/keyboard.h>
 
+#include "engine.h"
+
 static void draw_menu(int selected)
 {
 	extern bopti_image_t img_title;
@@ -31,7 +33,7 @@ static void draw_menu(int selected)
 	}
 }
 
-int main(void)
+static int main_menu(void)
 {
 	extern font_t font_mystere;
 	dfont(&font_mystere);
@@ -52,5 +54,59 @@ int main(void)
 			selected++;
 	}
 
+	return selected;
+}
+
+/* Returns a direction to move in */
+static int get_inputs(void)
+{
+	int opt = GETKEY_DEFAULT & ~GETKEY_REP_ARROWS;
+
+	while(1)
+	{
+		int key = getkey_opt(opt, NULL).key;
+
+		if(key == KEY_DOWN)  return DIR_DOWN;
+		if(key == KEY_RIGHT) return DIR_RIGHT;
+		if(key == KEY_UP)    return DIR_UP;
+		if(key == KEY_LEFT)  return DIR_LEFT;
+	}
+}
+
+int main(void)
+{
+	GUNUSED int level = main_menu();
+
+	struct player singleplayer = {
+		.x = 2,
+		.y = 3
+	};
+	struct map map = {
+		.w = 13,
+		.h = 7
+	};
+	struct game game = {
+		.map = &map,
+		.players = { &singleplayer, NULL },
+		.time = 0,
+	};
+
+	int level_finished = 0;
+
+	while(!level_finished)
+	{
+		int turn_finished = 0;
+		while(!turn_finished)
+		{
+			engine_draw(&game);
+			dupdate();
+
+			int dir = get_inputs();
+			turn_finished = engine_move(&game, &singleplayer, dir);
+		}
+
+		/* Update doors, etc */
+	}
+
 	return 1;
 }