Reccomended Game Gear/Master System games

[Badassbill]

Alex Kidd in Miracle World
Alex Kidd in Shinobi World
Ghost busters
Penguin Land
Psychic World
Phantasy Star
Sonic the Hedgehog
Wonder Boy
Wonder Boy in Monster Land
Ys The Vanished Omens
Zillion

There's bound to be more, but here are some good ones.