The Darkness is not a bad game and it should be very cheap now.

I give this thread a 9.6.

Dead Rising would be your best bet, it's open ended and fun enough you can keep going back to it, plus you get to keep your character instead of starting a new one over and over again.

As for the others games mentioned, if you have a PC, get them on that instead of 360. Main reason being that player made mods will keep you coming back long after the initial game wears out its welcome.

There's some interesting stuff in the works for both, and to give you an idea: Counter Strike and Team Fortress started as mods.

Condemned 1 and 2. Should be pretty cheap too.

Call of Duty 4

-Call of duty 4
-Ninja Gaiden 2
-Mass Effect
-Bioshock

If you want shooters go with The Orange Box (the half life compilation) you'll enjoy it, also if your open minded to other genre's Tales Of Vesperia, Lost Oddessy, Too Human, and Madden 09. (You said you played Rainbow Six Vegas, but what about Rainbow Six Vegas 2?)