Previous Gears games, Unreal Tournament 3, Shadow Complex, the upcoming Bulletstorm... It's the usual current-gen suspects. I'd be willing to bet that we're looking at new character and weapon skins for multiplayer (particularly given that Gears' Marcus and Dom made an appearance as reskins in Lost Planet 2), but hopefully there'll be something a bit more imaginative on offer too. A 2D Gears level for Shadow Complex players? A "tether Locust and kick them at Dom's bayonet" minigame for Bulletstorm players? Basically, no chance. But we can but dream.
Of course, if my guess at the unlocking mechanics is correct, it would be entirely possible to subvert this little Epic Games loyalty scheme by just borrowing or renting copies of the above (bar Shadow Complex), setting up a save file and waiting for your free stuff. But then again, that still means more people playing and probably enjoying Epic games, so as viral marketing goesit's still a sound tactic. Gah! You win again, dark lord Bleszinski!
What do you reckon this little lot will entail? And what are you hoping for? However crazy, all ideas are welcomed.