Started work on a Blitz Basic library for Mega Drive, source code and example "hello world" project (based on a
BigEvilCorporation tutorial) is
here.
Still early days, and it is very prone to breaking, but I'm hoping it'll eventually become mature enough to make a game with. It's largely based on the Super Skidmarks port to Mega Drive (including the way they inserted a pointer to a fake exec.library at $4 in order to have a fake version of allocmem at a place where Blitz Basic would expect it to be).