Am I just searching wrong or has there been no thread about this yet? http://affinix.com/ It's a proper GBC RPG which there isn't many... or any of as far as I can think off the top of my head. The guys who made it released the game and it's source code, it's programmed to end at 1/4 of the way through as past that there are some unfinished things but it's 90% complete, and it should be possible to edit out that ending (said it's to protect your save game etc) and even fix it and finish it yourself. They might even finish it themselves at some point. I think I heard Kickstarter mentioned at some point as well, although considering the game is virtually complete I'm not entirely sure what that would even be for but hey, I know nothing about game development. Maybe that was for physical release or something.
Was just searching around and I noticed this https://github.com/infinity-gbc/infinity/blob/master/source/vars.h "extern UBYTE reset_ok, _gba;" Now, the guy who released it has edited it a bit as I said to clean up some parts, but assuming that's actually from back when it was in development, looks like it was able to detect a GBA or something. I have no idea what that actually is or does though, maybe it was for the pallets or something. Can't even remember how GBC games look on GBA honestly.
That indeed seems to be the case. I saw mostly palette selections; there's also a gradient being modified at one point (e.c line 397), slightly increasing all the values. This leads me to believe all this is just to brighten things up a bit to try and compensate for the first gen gba's crappy screen.
I tried to buy the rights to this game a few years back he wanted "a few hundred K" I guess his hubris finally caught up with him.