Pokemon Blue

Pokémon Blue is a 1996 role-playing video game for Nintendo's Game Boy, released alongside Pokémon Red as the first entries in the Pokémon franchise.

Players capture and train creatures called Pokémon, battling other trainers to become champion.

Blue and Red were nearly identical, differing mainly in which Pokémon species appeared, encouraging trading between players: I had Blue but my brother had Red, so we'd trade to complete our collections.