Yes SD cards fit. I have no clue how big the game will be. I know the Wii U game takes 7,8 GB of space without the DLC. So I suggest you buy a card with enough space.i have the old 3ds xl with a 4 gb sd card on it and a couple of games that i always use so i dont want to delete them. I also have another 2 gb sd card which i was wondering if i could use them both on the same system without any problems. Btw i hope hwl will fit on a 2gb sd card lol