What single player games should have online game modes?

[Skobvs]

S.T.A.L.K.E.R. would have been fantastic to go through in co-op mode. But like the devs said, the engine couldn't do it due to syncing issues. (something like that anyway)

Lets just imagine this for a moment, it a stalker MMO,but there would be a point behind backstabbing fellow stalkers for artifacts and whatever, faction wars, mutant raids. yeah, but when theres lots of guys running around doing the same thing, it would kind of detract from the atmosphere, which is why its an awesome game

What I meant was not for an MMO but a 2-4 people co-op game. A stalker MMO would be horrible, I agree with that but with co-op of a few of your better friends can be great for games like this.