On Feb. 27, 1996, a trio of quirky creatures crept out of Japanese designer Satoshi Tajiri’s head and onto Nintendo’s crazy popular Game Boy: Bulbasaur, Squirrel and Charmander became the first of development studio Game Freak’s exotic monster-pets you had to catch, then train to do your bidding in disarmingly cute, tactically intricate battles.
In the two decades since, the Pokémon series has soared to become second in record-holding franchise sales only to games starring Nintendo’s indefatigable mustachioed plumber, Mario. And it’s still going strong, poised to finally land on smartphones and tablets later this year with Pokémon GO, an augmented reality game about deploying players to hunt Pokémon in the real world, and a critical part of Nintendo’s delayed foray into the wild and wooly mobile-verse.
In 1999, a TIME cover story explained how the whole thing started:
Read the rest of the story here, in the TIME Vault: Beware of the Poké-mania