Yesterday I stumbled over an interesting game, perhaps the first to offer a positive ROI since I started with the Left 4 Dead series: that is to say, I'm really enjoying this game lol.
Killing Floor is similar to the zombie mode in Call of Duty but without the run & gun feel; which is rather surprisign considering it's built off a modified Unreal Engine 2.5. It actually makes RvS/SWAT4 look more like a R&G game IMHO. The jist of the game, your rag-tag squad is dropped into wave after wave of "Specimens", the most basic of which resembles a vampire out of I Am Legend and behaves like a Night of the Living Dead zombie; the majority however, are closer to mid-level Strogg from Quake II/IV.
For all the specimens you kill, you earn Pounds Sterling that can be spent on weapons, ammunition, and body armour between waves. Although it is only a co-op/horror type game, it's not as team work oriented as Left 4 Dead, which was designed to *force* you to work together. It is however extremely fun when played with a good team. Also unlike Call of Duty's concept for co-op, it's not oriented towards competitive co-op but more realistically, completing the objective and living to tell the tail.
Me like :-)