Last night we checked out a mod for Quake 2. Yes, that Quake 2. Called Co-Op Or Die the mod allows co-op play on a persistent world server for up to four players per instance. Along with the entire Quake 2 campaign, players can play various challenge maps created by the community. The whole thing is tied into the official Co-Op or Die website which allows chat, stats, and other info all integrated right in.