Simplify the following text for a Grade 5 native English-speaking person.
Original: The PokÃ mon series began with the release of Pocket Monsters Red and Green for the Game Boy in Japan . When these games proved extremely popular , an enhanced Blue version was released sometime after , and the Blue version was reprogrammed as PokÃ mon Red and Blue for international release .
Simplified: Later , a sequel to Red and Blue was released : PokÃ mon Yellow .