gamemodes could be last man standing, king of the hill (or varios other marker based game modes), and some form of hoard survival. i would love it if you used something close to the zombies formula!!!
good job on the full game! i first downloaded when the halmets where the only things that were different colors on teams and im happy to say this game has grown for the better! another suggestion would be the pre-installed maps being colored in future updates.