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Perhaps Borderlands i enjoyed both its fps/rpg.

Borderlands 1 and 2 would be a good suggestion.
I've played the second and I enjoyed it a lot- which says a lot since I don't usually do RPG
sweatdrop
Gears of war trilogy would be an interesting FPS game to get. (the 1st and 2nd aren't even expensive due to how old they are so you could get it for cheap) :3
Ah, you could also get into the bioshock trilogy ^^ they're also good games/stories :3

Fallout 3
Loved the game. You're trying to find your dad and figure out why he left the vault without telling you anything. You can get it with all the DLC for $20 now. (F3 Collectors Edition)
Oblivion
Made by Bethesda as well. Almost the same as Fallout (Well its Elder Scrolls so..). Again, $20 for the game+DLC (Oblivion: GOTY Edition). You basically escape from prison from the help of the emperor. He then dies, you have to find his heir or the kingdom will go to ruins, etc. On top of all that, you're the only one who can close these things called "Oblivion Gates"
Fallout: New Vegas
Yet another Bethesda game. Very different from F3 but its good. As the name hints, you're in the Vegas area. You're looking for the guy who shot you in the head and trying to figure out why he wanted you dead. I bought mine for $40 and it included all the DLC but that was when Ultimate Edition came out. I think its $25 now.
Tony Hawk's American Wasteland
Even though this wasn't on your list, its an awesome game. I wasn't even into sports games before I played THAW. Gamestop sells it for $14 used, and its a rare find. It'll make you rage, but its all worth it.
Halo 4
People say Halo 4 is crap. It is. In some ways. I kinda enjoyed it however. Its a continuation of H3 (obviously). You get new enemies, spartan ops (A continuation of the campaign), etc.. I bought Limited Edition (The $100 version). My Gamestop miraculously still has a copy of it brand new for $30 So I think it'll be that much on Amazon as well. And its worth it. It gives you all the DLC (Technically the season pass ($20)), a 2 week to XBL (Don't know how much this is valued at), an avatar costume, an avatar prop, steel book of H4, a spartan ops movie, and a few random stuff that involves the game (Like letters and stuff).
Alan Wake
Another game you might not like but I loved it. My boyfriend and I both bought ours at Newbury comics for $30 (Limited Edition). His was brand new I bought mine used. We both got a DLC card, a book, the music soundtrack, and another disk that gives you an impossible to get avatar shirt (because its restricted to this edition). Anyways, if you get it, get Collectors edition. The game is awesome imo. I can't really explain whats going on w/o spoiling though xD

Hope I helped kinda ._.

I've never played Bioshock, but I've heard enough good things about it to recommend it. I'd also recommend Skyrim and Darksiders.