empty_space = 0
wall_tile_01 = 1
wall_tile_02 = 2
etc

level_01_BG_0-0.bmp
level_01_MG_0-0.bmp
level_01_FG_0-0.bmp
level_01_collision_0-0.bmp

level_01_BG_0-1.bmp
level_01_MG_0-1.bmp
level_01_FG_0-1.bmp
level_01_collision_0-1.bmp

level_01_BG_0-0.bmp
level_01_MG-collision_0-0.bmp
level_01_FG_0-0.bmp

level_01_BG_0-1.bmp
level_01_MG_collision_0-1.bmp
level_01_FG_0-1.bmp

258 = 0,1,2
259 = 0,1,3
260 = 0,1,4