f you want to play Alien Swarm as a FPS then do the followng:

In a running game of Alien Swarm simply go to Options > Keyboard > Enable developer console. Then hit ` (to the left of 1) and type:

firstperson

asw_hide_marine 1

asw_controls 0

Its an interesting game ,and the coop works well ,you must work as a team just like in L4D(fecking Noobs).so if any1 is up for a game of alien swarm give us all a shout :D

You can now download Alien Swarm for free:

http://psteamproxy.yuanyoumao.com/app/630/

Looks like a good co-op, heads-down shoot em up.