>>43426251First image is the pre-97 build. It was likely made at the same time as Pokemon Blue (in japan, that was released in 96), and in the same folders you can find backsprites that look almost exactly like the front blue sprites. Ever find it weird how all Gen 1 games used the same backsprites?: Well, it seems like they tried to update them at this time and they were left unused.
Fast forward to '97. This is when the spaceworld demo was revealed and Gen 2 was in heavy development. There was a process of cutting and replacing unused pokes from the pre-97 build in a process of elimination that was leading towards the builds we're more familiar with. It was slated to be out the next year, but there were memory problems that resulted in Gen 2 being delayed. Thus, Pokemon Yellow was developed and released in '98 as a replacement. This is why many of the Gen 1 pokes in the spaceworld demo are similar to yellow version pokes, but overall were still mostly different.
After Iwata created a new compression program, development was revitalized. There is an unseen '98 build, though we have assets for it. Then there was a spaceworld '99 build that is very similar to what we got, with a few key differences. Pokemon like Wobbuffet (pic related), Kingdra and Sneasel hadn't been finalized yet. A full build of this demo was included in the source code leak.
