Hello!
I came across this post while looking for something else, haven't been on this site for a while.
I made synthosaur. The version on the cartridge isn't very good, I didn't know anyone was selling it.
I made it quickly using batari basic and hadn't really thought through the design much, I just wanted something to use the TIA sounds quickly and wanted some colourful visuals. I made a custom controller with 16 arcade buttons to trigger the sounds and used all of the atari 2600's function keys to adjust settings. It is atonal, so a little difficult to make anything really 'musical'
The COLOR/BLACK & White switch toggles between paddle and joystick mode. In KevKelley's video, it is in paddle mode - which was an after thought. Don't know why I put the default mode to black and white, but I wasn't thinking about other people ever using it. The difficulty switches changed the length of the sounds. I ended up abandoning this version and made one that used 2 star raiders keypads instead. Can't seem to find that version anywhere. I never got that put on a cartridge, I just used a supercharger. I attached the old rom, feel free to use it. I found a test audio track too(with reverb or something added, i dont remember)
I've been thinking about remaking a keypad versionit, if I do I'll make it a little more user friendly and share it!
synth1.bin
0000.mp3