Ten years ago today Microsoft changed the console war from a battle between two, to a battle between three. The Xbox, a big black box loaded with a "duke" controller became a staple of hardcore gamers. It contained a hard drive and a network connection, and it was the beginning of a big change for consoles. The system saw many great co-op games over it's life span, though none may be more iconic than the one it launched with in Halo.
To celebrate the system's birthday we want to know which co-op game on the Xbox 1 was your favorite. Perhaps you can tell us why in the comments section. There's a lot to choose from, so choose wisely!