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?
Thanks for pointing out the rogue typo, I use swipe texting on my phone so I occasionally get stuff wrong and I tend not to proof read as much as I aught to. Either way it's fixed now.