Monkfish Acc. said:
Perhaps an MMO, so that it's constantly updated and never the same twice.
That's the realistic answer, I suppose.
Does the game come with a map editor? I'd probably take Fallout 3 if I can create my own things.
Starcraft seems to not get old due to the fact that I can practice forever.
Will the game continue to have multiplayer? Will I have people to play with? What if the servers are shut down for it?
More specifics are required.
I think Daggerfall if it has to be offline.
Starcraft or SupCom otherwise.
If new content/maps continue to be made, I'd probably take Mirror's Edge (Yes, I'm serious.)