Ajna said:
Take a sprig of "Bad Company", toss in a mixture of "Oblivion/Fallout 3", and stir counterclockwise for three full turns.
I give you: Bad Company, but with more than 10 hours (top) of gameplay, and a free-roamable world in which you can blow up everything.
Aka the way Fallout 3/Oblivion should have been? More games should include fully destructible environments. Red Faction did it right, though.
OT: Take TF2, splice in some Half-Life 2 [And all the episodes], then, mix in some COD5 and 4, and put in a bit of BioShock and L4D.
It'd be set in Rapture, with two teams of survivors trying to survive a zombie/splicer apocalypse with Big Daddies, terrorists, and Combine all fighting each other. Now that's a game