Killing Floor!!!

If you want something very laid back to vent out your frustration with the world on...  I strongly urge you to check this game out.

The premise is extremely simple; some crazy company set up a cloning machine for zombies (know as "zeds" in the community) and the machine malfunctioned and wiped out the majority of England.  You and your teammates (up to 6 players per server) are all that is left to fight off the waves of zeds.  Games last up until 10 waves are completed, each wave is progressively more challenging, and then you fight the boss zed - the Patriarch.

If you're patient you can snag this game for less than $5.00 on Steam these days and the player base is still very strong.  Also, if you like user created material the steam shop has lots of goodies to experiment with.

Tripwire Interactive is the developer and here is a link to their community board for the game:

http://forums.tripwireinteractive.com/forumdisplay.php?f=50

It's on sale for the St. Patty's Day Steam Sale - 75% off!

http://forums.tripwireinteractive.com/showthread.php?p=1298802#post1298802