Hi Joey, I don't know if I ever replied to you before... I guess someone also asked me for Pitfall 3... I don't know if I still have the game file since it was just an edit of Cliffall.... Are you still wishing for it? sorry I haven't seen this post until now!
Indeed, I was tweaking a open source pitfall 2 on blitzbasic and was interested in cliffall as a continuation.
Ok, good news and bad news!
The good first: I had the file! so I uploaded it here: Pitfall 3
Bad news: the game does not run on the Atari 2600. It was not meant to be a continuation. It was not made using a programming language either, but rather a drag and drop visual game building program. But I might at least bring the visuals very close to the Atari 2600 (using its color palette and perhaps respecting the scanline coloring. But I won't recreate flickering, lol