I've got too much completionist OCD and am too much of a storyfag not to finish games, so it has to be downright horrible for me not to finish.
Didn't finish:
- Oblivion
- Skyrim
- SR: DF & HK
- M&M X; just couldn't get into it anymore
- IWD series which I missed when they were new and I just find kinda boring now.
Really regret finishing but couldn't stop myself:
- Pillars of Eternity
- Fallout 3 (won't even touch 4)
- Dragon Age (2 and 3)
- Mass Effect (2 and 3, first felt somewhat original and good for what it is)
Currently in progress of:
- D:OS EE (finished the first regular edition already and curious about story changes) and kind of struggling to finish it, playing the tactician difficulty or whatever it's called and combat is starting to feel a bit tedious; which is too bad because it's what I loved about the game originally...
- Can't really get into Lords of Xulima no matter how hard I try, will try again later.
- AoD keeps killing me!
- Got pretty far in UnderRail, now waiting for it to be finished to start again. Really hoping familiarity to quests/story doesn't kill it for me but replayability seems high enough.
Completed: Pretty much most of the RPG's listed by others here I guess, save for Wasteland, Wizardry (never came across it as a child?) and JRPG's (including Dark Souls into this) which I simply can't get into.