It seems that The Pokémon Company just keeps on leaking, as yet another demo for Pokémon Gold & Silver has leaked online, with all new unused sprites.
In 2018, the Space World '97 demo of Pokémon Gold & Silver demo leaked online, which contained numerous unused sprites for Pokémon, as well as a wealth of content that fans never knew existed. This was followed by a leak of an early demo of Pokémon Red & Green, which also contained a ton of beta content. Since then, there have been early sprite leaks from Pokémon Diamond & Pearl, and a recent source code leak of Pokémon Yellow that hinted at a lost game called Pokémon Pink.
There has been a new leak demo leak of Pokémon Gold & Silver, this time from Space World '99. This one also contains lots of unused sprites, including early designs for Pichu and Celebi. A folder of the new unused sprites can be found on All The Pics (thanks Nintendo Everything), and there are some gems hidden among them. A few of the sprites have been shared on Dr. Lava's Lost Pokémon Twitter page, as seen below.
It's clear that this version of the game is a lot closer to the final product, as its roster resembles the one players saw in Pokémon Gold & Silver. A few notable details include Larvitar lacking a horn, Hitmontop resembling its design from the Space World '97 demo, Octillery and Remoraid resembling a tank and gun (also from the old demo), Pineco's rough design, a couple of new Pokémon with basic designs that look like placeholders, Aipom resembling its beta design, a whole new design for Sunkern, and an awesome unused sprite for Feraligatr.
It's incredible that these Pokémon leaks keep on happening, especially as Game Freak is such a secretive company and has kept these things out of the public consciousness for so long. This new demo is still being explored as we speak and it's exciting to think of the other secrets it could uncover. It seems that the Johto region has more mysteries than fans ever expected.