A really amazing, content packed, and downright masterpiece of a game is Prey. Not exactly what you're looking for, but it's hands down my game of the year.
It's sifi and has loads of content and actively encourages you to explore and actually use your brain to find stuff. Back tracking is actually fun because you see more than you did before.
Also, if you liked Dishonored, BioShock or System Shock then you will LOVE Prey.
Otherwise, I have nothing for you, sorry.