What games can you recommend that didn't get the appreciation that they deserved?
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?
I love the outer worlds, it has such a unique style to it, very much fallout humor in space with a little bit of arcanum thrown in for good measure. IMHO outer worlds > Starfield, when I saw that neon was just one long hallway with a few neon lights and signs, I knew what I was getting into and just stopped playing. Starfield has no identity, it's bland, space combat is annoying at best, and it's just an unoptimized mess. Outer worlds is unique, and when I see it I know exactly what it is, I can't say the same for Starfield.