For me, I'd have to say Old School X-COM (UFO Defense, TFTD, X-COM Apocalypse to an extent). I love them in a way that I just do not enjoy NewCOM, but the interface was quite possibly based on the recovered works of a 13th century scribe, and is very difficult to get used to for an unfamiliar player.
Check out PK Scramble if you haven't. Very nice way to re-play the game over and over.
ok this looks wild. but it says a playthrough is only 7 hours? how does that work?
Instant text speed, run button, and you knowing the game already to some extent.
Also the speedrunners can do the full 8-sanc run in under 2 hours.
fucking how