Yeah I know I'm late to the party for those who already know about this game, but for those who aren't familiar with Alien Swarm, I suggest picking it up.
Alien Swarm is comparable to a "top-down" L4D-esque cooperative game. It's free on Steam and requires some decent specs to run it on full settings, but once you get it going, I have to say that it's a decent timewaster. It has 4 player co-operative online and a very easy to use map editor.
For those interested, check it out for yourself:
http://store.steampowered.com/app/630/
Alien Swarm is comparable to a "top-down" L4D-esque cooperative game. It's free on Steam and requires some decent specs to run it on full settings, but once you get it going, I have to say that it's a decent timewaster. It has 4 player co-operative online and a very easy to use map editor.
For those interested, check it out for yourself:
http://store.steampowered.com/app/630/