Remember to read all responses to this question before giving an answer
All examples off the top of my head:
Bioshock (save the lil sisters vs kill them)
Fable 1,2 & 3 (literally everything)
Dante's Inferno (heaven vs hell/angelic vs demonic)
Catherine (not the best example but you had an a or b choice)
Mass effect 1,2 & 3 (renegade vs paragon)
List any games for all devices, new or old, that relate to this. From PC to phone games, Xbox to PlayStation, even lesser known systems like the Sega Dreamcast or anything. Please try to leave any illegal games off the list (I don't know if there are any) I'd like to avoid sending an unexpecting person into trouble.
Let's get it started!