A Pokémon Gold demo that was first showcased at the 1997 Spaceworld tradeshow has been uploaded and unpacked by The Cutting Room Floor

Something that would’ve been great to see in game but didn’t make it to the official release were baby forms of Vulpix, Tangela, and Goldeen just to name a few.

ResetEra User The Shadow Knight has spent 15 years studying the demo before finally getting his hands on it recently. He has compiled a list of all Pokémon sprites available in the game which you can see below.
It’s very interesting to note how many Pokémon ideas were adapted for the official release. One of the things discussed by Shadow Knight is the change to the map size. Originally, it appears that Game Freak intended to have a map that resembled Japan to be the Gen 2 region.
They even wanted to throw in the Kanto region in the game but for some odd reason, decided to condense the whole place into a single town! Definitely a rather bizarre idea.
For more info revealed through this demo, check out Shadow Knight’s complete post on ResetEra. He goes into extensive detail about all of the little oddities found in this early version of the 2nd Gen Pokémon games.