I've been recently been thinking about Arkane Studio's Prey which is a immersive sim, with a pretty good rogue like dlc, that probably has one of the strongest hooks of any game I've played. If you liked Halflife, System Shock, or Deus Ex it's definitely worth a play.
Are there any titles that might not have been commercially successful that you feel everyone should give a shot?
It's on archive.org if you ever want to play it. Not sure if it's DOS or Windows, but either way, an emulator will take care of that issue.
https://archive.org/details/i-have-no-mouth-and-i-must-scream-usa