Mockup screens of games from other systems
We've already been doing this in the Master System forum... So why not do it here as well? Take a game from another system, most likely SNES or perhaps PC Engine, and make it work within the Genesis palette limitations. It's a fun exercise with interesting results.
Here's one I did of Seiken Densetsu 3, which seemed like one of the toughest to do given the elaborate art direction and the amount of different characters on screen which really played to the SNES's strength in color output. I managed to reduce it from 88 down to 48 colors onscreen, which leaves some room left for any hypothetical situation with more enemies and projectiles onscreen (and assuming they would share some palette slots with the sprites already displayed).
http://i.imgur.com/C89ZRB6.gif http://i.imgur.com/ulnwHuA.gif
Maybe the vegetation turned out a bit garish, but I had to make the grass and trees share mostly the same shades of green and make them both work together that way.