Search about the shooting section...play the sequel if you haven't. Scout out the games that have been played the most number of times. I'm not an avid gamer so that's all I can do.
I agree that the next one should be multiplayer. how ever, armor mayhem is a almost a copy of raze. little different layout. little different maps and weapons. other wise, they are practicaly the same.
Also, if you check out the AG3 beta, that has a more refined search system. It has the usual categories and then some more in depth ones. Also, you could see if the maker of raze 2 (forgotten his name) has made any other games. Raze 1 in also good. There might me a raze 3 out soon. I have completed raze 2 but still have fun playing around on it.