It's really interesting when games have major changes when they come to the US. The biggest overhaul I've seen for no reason whatsoever was Magical Hat Flying Turbo Adventure for the Mega Drive. It was developed by Vic Tokai along with Kid Kool (NES) and Psycho Fox (SMS). By the time it got to the US, it was Decapattack starring Chuck D. Head. Everything was changed except the layout and design of the stages... most of them anyway. The graphics were changed completely (but the potions had the same basic graphical effects such as dual screen line scrolling, etc), the gameplay was completely changed to allow for a life meter of sorts, and even the music was changed. I personally like Decapattack starring Chuck D. Head better than Magical Hat Flying Turbo Adventure, but I have a love both games!