After many hours playing with friends, this is probably one of the best cooperative FPS around.
It requires the 4 players to stay together and help each other as much as possible to succeed, with nearly every solitary run ending on the floor waiting for backup to come and rescue.

Network support is better than probably all other games, with easy setup of online or local games, public or private.
Players can come and go as they like, the server moves between the available players to let them continue the match.
Bots automatically take the place of any missing players and if somebody needs a break, they will fill in the role to allow for the team to function at its best at all times.

Linux support makes it the perfect cross-platform coop game.

If you never played it, then do so.

After many hours playing with friends, this is probably one of the best cooperative FPS around. It requires the 4 players to stay together and help each other as much as possible to succeed, with nearly every solitary run ending on the floor waiting for backup to come and rescue. Network support is better than probably all other games, with easy setup of online or local games, public or private. Players can come and go as they like, the server moves between the available players to let them continue the match. Bots automatically take the place of any missing players and if somebody needs a break, they will fill in the role to allow for the team to function at its best at all times. Linux support makes it the perfect cross-platform coop game. If you never played it, then do so.