In "The Hidden", players choose the role of either a near invisible killer, Subject 617, or one member of an Intercept squad who have to capture him, I.R.I.S. In the simple but challenging gameplay of an 'one against all'? mode, Subject 617 creeps/sneaks through the maps armed only with a knife and three pipe bombs. The IRIS team carry a selection of weaponry, fully customisable at round start, from F2000 assault rifles through to shotguns or sub machine guns as well as a pistol as a secondary weapon. However, they can hardly see Subject 617 as, just like the 'Predator', only the outline of his silhouette is visible. On top of that the Hidden also moves a little faster and has many abilites such as pouncing, wall grabbing, corpse pinning and the fatal pigsticker attack. Therefore co-operation is necessary for I.R.I.S. if they wish to prevail (if they dont want to become the prey/victim themselves). This leads to an outstanding gaming experience on public servers:...
One the most fun Source mods out there, even in just a beta form.
Easily deserving a 10/10.
Tip for IRIS players: Hunt the Hidden, don't let him hunt you.
Fun thing for Hidden players: Get really good at playing as the Hidden, then play against about 3 noob IRIS players, and scare the hell outta them. :D
This is a mod with huge potential, but this was made a long time ago and the people how made it rarely update or just do any maintenance. That being said its still fun, you will encounter a lot of bugs that will frustrate you. I recommend you try it out, once you get the hang of it, it will be a blast.