it would be cool: for instance, what it would be like to startle your friend ny playing a game of sensible soccer with the field purple?
seriously: little tweaks for gaming only, like to make colours warmer or colder.
drastic changes for some research purpose: i would like to see what does it changes in gameplay with different colour schemes, i played around it on screenshots when i was making the backgrounds for Annihilation and when i made those mock-ups for a 4 colours shootem up.
mostly, anyway, just because it would be cool. anyway, i'm asking for it only if it's not too much of an hassle to add.