No. 10 Pokemon Blue

Publisher: Nintendo
Platform: Gameboy
Released: September 1998
Units Sold: 5 million
Genre: Role-playing

What made it cool: Gamers had to play Pokémon Blue in conjunction with Pokémon Red to gain access to all 151 fighting creatures. The games used Gameboy's Link Cable, which hooked two units together for players to trade creatures or battle with each other.