Super Retro Kid is officially done in its full 7 zones! Go check the Game Jolt page seen in the download link.
Now there is a thing: On limited systems the performance isn't that great and the reason seems to be due to the palette swapping for Jake and has been a problem since Demo 2 so there will be an alternate version without Jake. As he isn't important to gameplay the game will be unaffected in that aspect but "improved" in performance.
Enough, have fun!