I wonder where Tuper Tario Tros[1] stands from a copyright standpoint, then. At what point would you say that a game violates copyright? Obviously Super Mario B

I wonder where Tuper Tario Tros[1] stands from a copyright standpoint, then. At what point would you say that a game violates copyright? Obviously Super Mario Bros was the inspiration for a whole generation of platformer games that came after it. What would be the minimal set of changes that will allow Full Screen Mario to exist without violating copyright? [1] http://www.newgrounds.com/portal/view/522276 http://www.newgrounds.com/portal/view/522276 (flash required)