So for FF5, all the hacker has to do is to add the bonus dungeons! And as mentioned, the dungeons use assets that area already part of the vanilla game so it shouldn't be too hard for an experienced hacker.
Actually it is not that simple ... at all!
FF5 for SNES has many hard-coded limitations that are not visible to the player and probably are know only by few dedicated researchers:
- 512 possible battles (aka enemy formation) (vs 768 in GBA)
- only 7 monsters per formation and more: max 6 visible at the same time
- ONLY 256 normal enemies!
- total of 384 monsters (vs 728 in GBA)
- Damage formulas: 127, while GBA has 20 more. GBA damage formulas are not well researched.
- evasion only on shields
and so on ...
If I scratch my head a little I could probably multiply this list, but the points is: it is so hard, the change is so huge, so why even bother? There is nothing in SNES worth doing it!
On the contrary - if the legend is true (that FF5 Steam version contain and emulate GBA ROM) then its worth to improve GBA version