Abuse is a dark 2D side-scrolling platform game developed by Crack dot Com in 1995. It features beautiful lighting, realistic animation and nasty alien-like creatures to destroy. It is now maintained by Sam Hocevar in an attempt to prevent it from vanishing from the Internet. Wii port by HunterZ based on Sam Hocevar's source at http://abuse.zoy.org/
Full source of the Wii port is now available in this project's Git repository. Some help with building is available in a wiki page.
Original source code and assets fall under an array of open-source licenses, the most "strict" of which appears to be GPLv2. See the COPYING file in the source code for more details.
Wii changes are CC-BY-SA.
More info (including instructions for installation and play) can be found on the Abuse Wii article on the WiiBrew wiki.