I'm playing the Linux version, it works great. I got all the way to Vicar Amelia with almost no issues (only one crash, and some cape physics are laggy).

That said the recompilation Github repos are totally legal because they don't share any of the game data. You need to dump the game yourself to play it, so legally they're kinda similar to emulators.

Feels really good to be back, it's almost been 10 years since I played BB!