Shame... All those sprites and tile backgrounds are just begging for a DMCA take down. Why not just put up the tools that disassemble those from the ROM instead?
If this were Nintendo then I’d agree but sega have always been really chilled about this so long as the community does t profit off their IP (which is a fair line to draw).
Because of this, you’ll fine tonnes of Sega fan stuff. From multiple active Phantasy Star Online servers through to entire fan-made Sonic games.
In fact iirc Sonic Mania started life as a fan game and Sega asked them to produce a full game.
Do you wanna develop that tool? The sprite and midi extraction is pretty complex in this game, it was much easier for us to extract them by hand and then in the future we will produce something which extracts them automatically. Until we have that tooling in place we don't plan to release any binaries.
If that happens we will keep the repo private and develop the tooling to extract these in an automated way. As others have said, SEGA doesn't police their IP in this way. Checkout this game which has existed since the early 2000s https://www.srb2.org/
Just omit the problematic parts from public? And perhaps you want to migrate to some more resilient and friendly host than github.com, while you still have a chance to redirect people. All it takes is one form submission to nuke your repo.
(Assuming you care about your work and sharing it. Sure "Sega is chill" so far but you are really pushing it here and giving them a great display of why they might want to reconsider)
SEGA seems to always have been a lot more generous with this kind of thing... Much of the disassembly or decompilation projects I've seen come out of old SEGA games include all the assets with them (e.g. look up disassemblies for the Genesis games), and ROM hacks are typically distributed as full ROMs - I've basically never seen SEGA use the DMCA against any disassemblies/decompilations/ROM hacks.