there’s a lot of neat design in super mario bros., but it often seems like we only talk about those first couple screens. (i am no exception.) the above is one of my favorite setpieces in the game, appearing almost at the beginning of world 4-2.
the centerpiece is the narrow hallway on the right, down which three goombas march toward mario. the player has to get past them: by this point the screen has scrolled far enough to the right that there’s no way back. the hallway is only three blocks tall; a fully-grown mario is two blocks tall. if mario tries to jump over the goombas, he will most likely hit his head on the ceiling and fall back down.
something else happens when fully-grown mario jumps into the ceiling, though: a block’s worth of ceiling is destroyed. the “solution” to this screen is to use big mario’s strength to carve a hole in the ceiling – to make the ceiling higher – giving the player the head room to jump over the goombas. they advance slowly, and the player has plenty of time to prepare for their arrival.
what if the player’s not big mario, though? that’s what the part at the left is for. the coins lure little mario through that tiny crawlspace (too small for big mario to enter) into a small room. in that a room is a hidden, but pretty obviously placed (it’s easy to hit the block by accident, even, trying to jump out of the room) mushroom that will turn little mario big before he confronts the hallway at right.
if big mario can’t pass through the hallway without touching the goombas, he reverts to little mario. so this mushroom is a reward, then, for figuring out how to get through the hallway unscathed. there’s another power-up block immediately after the hallway that will provide mario, if he’s still tall, with a fire flower – or provide little mario with the opportunity to become big again, if he can catch the mushroom (the block is right next to a pit, which to an immobile fire flower makes no difference).
if mario enters the hallway small? then he has a lot more head room, and can jump the goombas without too much trouble, but he doesn’t get the fire flower reward at the end. if mario gets here big? then he has the opportunity to drop into the little coin room, collect a fire flower and use fireballs to clear the goombas from the hallways, but he might miss the fire flower because the crawlspace doesn’t lead him there.
so you can see this area is staged really well. thought has been given to the state mario enters the hallway in and the state he’s in when he leaves. and the problem itself – remembering and taking advantage of big mario’s latent ability to change the shape of the world around him – is one of my favorites in the game. it’s almost a lateral thinking puzzle: what does a man who can break through bricks do when the ceiling’s too low?