Well, it does have a Diablo-style loot system and skill points. However, it is otherwise a pretty typical shooter, the RPG influences are pretty subdued. I like it a lot, but I wouldn't recommend it to someone who like shooters.
I would give this one a thumbs up, but you mentioned that you even have trouble with PoP :). This is essentially Zelda mixed with PoP plus a loot system. There's a lot of combat that requires fairly good timing, but I think there's an easier difficulty if you aren't great at action games.
Reever: Batman game (though those are pure action...but it's BATMAN xD)
These are probably my favourites out of your picks. There's a lot of action, but also a lot of stealth. Excellent games. Be warned, however, that Steam no longer sells the DLC for Arkham City separately. You would need to rebuy the GOTY edition, which is irritating.
Reever: Or I'll just get Civ 5. I loved Civ 4 (although I think I have always cheated, but it was fun :P).
The other games all look like shooters, so nothing for me there.
Civ V is quite different from 4, but you might dig some of the improvements. The fact that you can no longer have stacks of units makes combat far more satisfying.
Reever: Does that site have such promos more often?
They do promos fairly often, something like twice a month or so for 72 hours. You have to be careful to check what kind of DRM comes with the games (usually a Steam key, but sometimes not).