The way this game plays out is different than PR. Princess Rescue plays in a sequence. 1-1, 1-2, 1-3, etc. Zippy plays out more like SMB3. You start on an overhead map, going from spot to spot chasing after Eggman who's occupying one of the levels that you got to get to to get a gem back from. Then once you do he goes to another part of the map and the chase continues until you get all 5 gems, so it's possible to beat without playing all the levels. A demo would consist of a hardset configuration that every time you played it, it would play out the same and would end once you get a gem. The real game changes where Eggman will be every time you power on, so even where you start may be different than the time before. One time you may start on Hill Zone, another Star Zone, etc. As far as a 32K demo goes, that's going to be a tall order, because in order to do the different zone configurations, soundtracks, and the map routines, It's going to have to have 64k. I would have to program a completely different demo version instead. The level data is only going to take up 8k in total. The music probably about the same. Another bank for all the sprites and Batari's kernel, one more bank for all the playfield graphic configurations for the 4 different zones, and the rest for all the code and tables.
This can be the first Atari 2600 64KB single game (not cartridge, Stella's Stocking is 64KB of more than one game).
It wasn't too hard to switch over, was it?
Too bad real hardware will have to wait for a real cart.
Will you be able to release a World in 32K like with PR?