Gravediggers

"Gravediggers" was the product of thatgamecompany's internal 24-hour game jams, which took place in 2008 with two main goals, according to studio co-founder Kellee Santiago: "To see how much fun we could generate in 24 hours," and "to make something multiplayer we could play in the office." You play as a pistol-equipped grave digger who runs around killing zombies; each time you shoot one, its head pops off for you to collect and deposit in one of two crypts.