Unused Stuff in NeoGeo games...

There are so many NeoGeo games which have unused graphics, sounds and even complete stages still on the game cartridge.
I wonder if there are some people here who know a little bit more about all this mysterious things.
Things have been discovered using the debug bios and by coding trainers for *cough* emulators *cough*.

KoF96...many unused moves are in this game. I don't know how they were discovered.

KoF99...I remember seeing a screenshot with an alternate version of Kyo's 'new' costume. It looked kinda cool. The CD-gallery of KoF99 had some alternate versions of character costumes, too but the one hidden on the cart was not among these. I think it was discovered using a trainer.

MetalSlugX...heavy stuff! There are all (!) MS1 missions on the cartridge, many scenes from MS3 (!) including the helicopter and the sub. Awesome! This was discovered with the debug bios.

ShockTroopers2...unused animation, a unused character (!), unused artwork and a complete unused cave-level. Discovered with the debug bios

Are there more games with hidden/unused stuff on the cart?

There are different reasons, why those have not been used:

In case of moves, maybe due to gameplay balancing. Maybe a char would become to strong with them.

But in general I guess it´s is a matter of missing time.


Like Square, who always give fixed release times, altough the games would not be finished then.

That´s why their xenogears was messed up on CD2, FF7 is unfinished since Ellis should have been come back (resurrected), etc.!