Pokémon Infinite Fusion

The game follows a very similar story beat to Pokémon Red/FireRed, except for the invention and widespread use of Pokémon Fusion Splicers.

Starting in Pallet Town, you receive your starter from Professor Oak, your rival proceeds to get the two you did not choose and fuse them for your first battle. Team Rocket are the main antagonist, attempting to fuse three legendary Pokémon by experimental methods to take over the region. The gym leaders and overall story contain some of shape of Pokémon Red, however some tweaks were made to account for the new mechanics, expanded map, additional Pokedex entries, and full post-game.

Résumé

Pokémon Infinite Fusion is a Pokémon RPG fangame based on the Pokémon fusion generator trend, featuring sprite art from a large community of artists. In this version of Pokémon, Silph Co. has created a DNA splicer that can work on any Pokemon, allowing their stats, visual appearance, and typing to be combined alongside their available abilities and moves. The game includes both the Kanto and Johto regions, and includes over 570 Pokémon, including the first 386 Pokémon from the first three generations alongside a suite of specifically chosen Pokémon from later generations.

With hundreds of thousands of fusions available, even Professor Oak doesn't expect you to "catch 'em all"!