Lets see, some obscure games i beat to death as a kid
NES- Kickle Cubicle, Mickey mousecapades, little Nemo the dream master
Genesis- Phelios, Shadow Blasters
Kickle cubicle is a really good room by room puzzler in the style of Lolo. But better in my opinion. You solve puzzles by turning monsters into ice and pushing them into the water to make a bridge.
Nemo is an awesome non- linear platformer. You feed candy to certain monsters and you can use their ability to travel the stage and look for the 6 keys to unlock the door at the end.
Phelios is a shmup where instead of a spaceship, you are Apollo, the Greek sun god on a quest to save Artemis. Essentially, it's a shmup based on greek mythology. Cool bosses, epic music, creepy levels, good stuff.
Mickey Mousecapades is a run and gun platformer very similar to Mega man, just not quite as good. It has its moments, though. The platforming is based on making sure Minnie can make the jump too, which is tricky since she's on a slight delay.
Shadow Blasters is one of my favorites of all time. It's like a combination of NES TMNT where you can choose between 4 characters on the fly and Mega man, where each character's attack is effective differently against different enemies are sometimes ineffective in different levels. Really cool levels, some interesting and frustrating bosses and cool music. Not a big fan of the final boss though.