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?
Brute Force for the original Xbox. 4 player squad based gameplay, with different squads full of characters with unique abilities. It was a ‘platinum hit’ but I’m pretty sure anything that sold more than 500 copies was