My son is into his Wii games, particularly Mario and wanted same theme for his 7th birthday. For his Super Mario Cake I used a quarter sheet pan and double layered it to get thickness to decorate the sides. Each side of the cake has scenes or characters from the Super Mario Bros. game.
Like the bricks with coins floating above it, the chomping flower coming out of a green pipe, the bullet guy, an invincibility star, the wall and flag pole you get at the end of a level, etc. I did it all by hand and there’s so much stuff in the game you can’t go wrong. You can even use different worlds on each side if you so choose to put in such effort.
The top of the cake was Mario himself. I started with a basic outline of him and filled it in with a star tip, adding details. The cake was all frosted first with a sky blue color because most of the scenery in the game includes a sky scene. I had a bit of cake mix left over so I made a cupcake and decorated as an extra life mushroom (the green one) and put a 7-up (age of child). The name alongside Mario was cut out of fondant with cookie cutters.