I see you've already got the Mass Effect series on your list, but I'm still gonna recommend it. Best series this gen for me.
I also recommend Darksiders. It's an excellent Zelda style game with great scenery and awesome lore. And you've got the sequel coming soon as well.
The Darkness I and II are worth playing as well. Maybe as rentals since they're short but the first game is only like $3 now for a used copy and not much more for new.
And Dead Space. Probably my third favorite series this gen.
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Gamertag/PSN-Murphiroth
"Would have liked to run tests on the seashells..."