ZSX4 Guitarpocalypse (Zombie Smasher X4 Guitarpocalypse) was created by Ska Studios. It's Ska Studios first attempt at the XBLA Indie Marketplace.
Like ZP2K9, this is a "beat em up" style game. You choose a character (ninja, pirate, zombie, ect) and then you choose your guitar. You can play this game in single player against bots or you can go online and fight against other players. This game is sold for 80 Microsoft points ($1).