I think that a maximum of 3 players in campaign missions is too low. Me and 3 other friends were trying to play campaign missions together, but no, we had to split into 2 teams. Unless you can have more players as the campaign progresses, I don't know. But seriously, what campaign can only allow 3 players? I thought this game was just optimised for 3 players, not could only allow 3 players. [spoiler]I know you can have more players in other modes.[/spoiler]