Alas, you have been suckered into an advertisement video for FreeInfantry.com But it may be the best mistake of your life.
This is the ULTIMATE online shooter, (not to be confused with first person shooter.) This game combines stealth, tactics, tanks, and numbers to get the job done. 100 players per arena fighting over some small plot of land. Worried about lag? Forget about it. Unless you live in Korea, in which case you should forget about this game and go play starcraft.