I'm sure it has been said before and if so, I'll say it again.
Could really dig multiplayer in this game. Not a versus. Just a coop. How fast can a team beat the mission. Team of 2, Team of 3, etc...
Another option is the same player configuration where both players play the same 'player' in the game. Helps in fighting multiple fronts. etc...
I like this game a lot so far. Really would love to coop with my friends in it.
-E
Note: posted this by accident in the Creeper 2 Suggestions forum. Sorry for double post.