Hidden:Source

A brillient game. Even though its a mod for Half-Life 2, great gameplay, atmosphere, weapons.
But heres the catch, when playing it, its 1 Vs. 6, one is invisible while the others are trying to hunt you down, you could be standing right next to someone then *BAM* they're dead and then you are.

The invisble one has a knife, while the rest are armed with hi-tech weaponry.

http://developer.valvesoftware.com/w/images/6/6d/Teamshot.jpg

http://developer.valvesoftware.com/w/images/a/a4/Hidden02.jpg

Have fun if you ever get this mod.