Clownacy posted this elsewhere, but there's been 4 updates since this post, with the latest one, v0.4 being done to be compatible with Sonic 1 asm68k's recently added smps2asm support.
Here's the post.
I've been working on a kind of silly hack where you play as Sonic, Tails, or Knuckles on a Pogo-stick through Green Hill zone. It's not finished yet ,but it should be fun.
In the end, you'll play through just Green Hill.... I think