Will BlastEm support the Sega CD?
Yes. This is planned as the next major feature.

Will BlastEm support the 32X?
Yes, but I don't plan to start on that until after Sega CD support is complete.

Will BlastEm support the Game Gear or SG-1000
Yes, but I don't have a certain timeline for these currently.

Can I use BlastEm in my commercial product?
Yes. Please See Commercial Use for details.

Why don't you use GitHub
BlastEm is a passion project so I use technologies I like even if they aren't always the most practical choice. I like Mercurial more than I like Git. I also like being able to self-host the core infrastructure of the project.