![Shocked :shock:](./images/smilies/icon_eek.gif)
I can't even imagine how this was coded (and debugged), this was surely crazy head scratching and endless experimenting to achieve this. If, as i guess, it relies on very precisely timed VDP writes (FIFO and registers) interleaved with the rendering processing, this is going to be a nightmare to emulate this correctly... Some color effects also are just astonishing, as if there were some analog video effects going on (controlled through new undocumented VDP register bits?). I can't wait for the technical details, especially if it involves new undocumented stuff and hardware variations between console revisions.
@Ralakimus: the version of Genesis Plus GX used in Bizhawk is quite outdated I think, newer versions enable SSF2 bankswitching by default for unknown ROMs so that demo should work (well, at least run) without modifications in the Wii version or with Retroarch for example.