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?
Games of any time period are valid. The two reasons I made the post were:
I actually heard about that game for the first time the other day in a YouTube video on philosophical questions in video games that I had playing in the background while doing other things.
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