Complex sentence: It is based mostly on the game-play of Nintendo's "Super Mario Bros." for the NES, the only major difference is the ability to control characters that debuted in other Nintendo Entertainment System games unrelated to the "Mario" series.
Split into simpler sentences: It is based mostly on the game-play of Nintendo's "Super Mario Bros." for the NES. The only major difference is the ability to control characters that debuted in other Nintendo Entertainment System games unrelated to the "Mario" series.