The Pokémon historians at the website Helix Chamber have come across prototype assets for the Generation I Pokémon games (Red, Blue, and Green.) Among these assets are never-before-seen designs for the original Pokémon.

These early assets come from an anonymous source, according to a Twitter thread written by Helix Fossil. Although the source wouldn’t pass along the full playable build to the Pokémon Red and Green prototype, they were willing to pass along the assets to the group. From there, Helix Fossil enlisted the help of ROM hackers in order to reconstruct the sprites in further detail, including trainers, Pokémon, and the original Kanto map.

The assets can all be found here. The names given to these Pokémon are made up by Helix Fossil for sake of clarity (even ones with known Japanese names), but everything else is official stuff.

Among some of the more interesting cut Pokémon is ‘Ohmega,’ a Pokémon themed around robotic kaiju like Mechagodzilla.

There’s also Pokémon like ‘Bloonder,’ a sentient balloon, and ‘Weirduck,’ which is suspected to be a midway evolution between Psyduck and Golduck.

Two particularly interesting Pokémon have to do with long-running fan theories. The first one here, ‘Guardia,’ is related to a fan theory that the sad Ground-type Pokémon Cubone is the grown-up version of the Normal-type Kangaskhan’s baby, wearing its mother’s skull to hide its tears. The fact that Guardia seems to have a child of its own seems to link the two motherly Pokémon together, in a twisted sort of way.

The second of these Pokémon is ‘Toartle,’ a Pokémon that was likely Squirtle’s original final evolution, instead of Blastoise. Judging by the fact that Squirtle and Wartortle had a good amount of Fighting-type moves, it’s suspected that this Pokémon could have been martial-themed, like the various Fire starters that become Fire-Fighting types.

Other cool assets include original NPC designs, like the original design for the player, a robotic trainer named after the Shinjuku commerce district in Tokyo, and a kid who was a prototype first Gym Leader.

More articles will likely come out of this discovery, but you can see all of the details here. A ZIP file containing all the assets can be downloaded here if you want to peruse them. If you’re interested in what never made it into the games, be sure to check out the leaked demo for Pokémon Gold and Silver from the 1997 Space World convention.