Decorations could be video game posters around the room and game discs hanging from the ceiling.
Music could be songs like video game themes, pop, rock, etc.
Food ideas are a cake with video game figures on it, punch, and a chip buffet.
While you are waiting for all of your guests to get there, have a few video game practice rounds.
When all of your guests get there, start out with something easy like bust a move bash or cooking mama cook off, then, move up to the medium level games, then, even harder. You can do any video games, just make sure you can either make them two players or there can only be one or two players.
Mine will be on my b-day!! YAY!! I am turning twelve!!