I'll take a shot at this. I recently picked up a game called Time Soldiers for the Master System. Never heard of it before (like many MS games) and I took a chance on it because it looked similar to an Ikari Warriors type game. Haven't played it yet.
Most of the classic games I'm still just finding out about are either Master System because I only recently started to collect games for it, or PS1 because there are just so many PS1 games out there. I guess you could say Genesis somewhat as well, I'm still finding games for it I've never heard of.