OpenBOR is a royalty free sprite based side scrolling gaming
engine. From humble beginnings in 2004, it has since grown into the
most versatile, easy to use, and powerful engine of its type you will
find anywhere. OpenBOR is optimized for side scrolling beat em’ up
style games (Double Dragon, Streets of Rage, Final Fight), but easily
accommodates any sort of gameplay style and feature set you can
imagine.

WWW: http://www.chronocrash.com/