The Genesis gets a raw deal when it comes to colors available and the use of those colors when you compare a cross platform game (see issue #1 of RGM for 15+ pages of such a comparison). Sega could have used better colors for their games, the Genesis has them available, but for some reason they did not. Fans have taken it upon themselves to improve one such seminal Genesis game, Streets of Rage 2, with improved colors.
This enhancement is quite a stark contrast to what was officially released. Just look at Axel (pictured). On the left is the original Streets of Rage 2 sprite, on the right is the enhanced one.
Probably the most striking thing is the lighter blue used for his pants and then the skin tone. Nearly every color has been enhanced in his sprite from his belt to his gloves and creases in his shirt.
To grab the patch that will allow you to play with this new enhanced color scheme head over to ROMHacking.net.