Originally Posted by ThreeSixty
Just remembered. The Wonderboy series. Wonderboy in Monster World (released for the Master System and Genesis) is one of the most underrated and greatest side scrolling 16-bit adventures of all time (IMO). The sequel was only released in Japan but you can play it via an emulator. There's even a fan-created English translation out there.
If you've yet to play those two games and are a fan of the Genesis; play them now.
Wonderboy in Monster World was awesome! I replayed it on my Xperia Play with an emulator last year and it's still fun too (major nostalgia glasses of course).