This is a very interesting and unique game,it's not your standard FPS like "Duke Nukem" or "Call of Duty"."Killing floor" relies greatly on teamwork. The player has the option of choosing from 7 different perks,each of them meant for a specific task.If one teammate fails his task or another is too selfish,then the squad is doomed.That's what I like about "Killing floor" so much.Unlike Modern Warfare,there is teamwork here and there are far less people who join a server for the sole reason to swear at others and brag about how great they are."Killing floor" also has many features that contribute to a more realistic FPS.There is no auto reload,how much you carry affects your movement speed and so on,and so on.Yes,it is a difficult game,but it's entertaining as hell playing it.The only reason i'm not giving this great game 10/10 is because of the glitchy hitboxes,a.k.a what determines if you score a headshot.Unlike other FPS games,in "Killing Floor" scoring a headshot is not an instant kill.There is chance that you score a crit. hit and decapitate your enemy.That doesn't always happen,combined with the somewhat glitchy hitboxes it kind of spoils the whole game.A more experienced player won't be bothered by this,however.Overall,this is a great game.I strongly recommend it.