Despite having a large cult following, a long history and historical critical acclaim, the Rayman series never quite finds its way into the big and popular lists of retro franchises fondly remembered. It doesn't quite have the mainstream recognition it deserves. As old as GTA and as much a pillar of early gaming, Rayman was an early heavy hitter for Ubisoft, which has now become a juggernaut of the industry.
While Ubisoft hasn't buried the franchise, it did push it back from the spotlight and took it down a... questionable path before veering back on course with recent installments. The franchise has its roots in the platformer genre, with the first game having been released way back in 1995.
Rayman's world is a fantasy one, but not schematic in any way. It is both magical and very much unique, with one of a kind characters and environments. Rayman himself is a vaguely humanoid creature with no visible limbs connecting his large hands and feet to his hoodied torso. He wears modern clothing while adventuring in a land of magic and wonder.
GTA V's fanbase, as proven by countless mods and fan videos paying homage to other retro series, has a penchant for reviving other franchises within Rockstar's newest blockbuster. As such, it was only a matter of time before some modder enabled players to explore the world of Los Santos as Rayman.