The story of the "99999 in 1" is not one of official Nintendo releases, but of ingenuity in unofficial markets. Throughout the late 80s and early 90s, the high price of original game cartridges led to the rise of "multi-carts" from unlicensed manufacturers.
While the label boldly claimed to contain 99,999 distinct games, the mathematical reality of an 8-bit cartridge meant this was physically impossible. The Architecture of a Bootleg Illusion 99999 in1 nes rom download top