https://www.gamespot.com/articles/new-super-mario-bros-gets-an-80-level-sequel-creat/1100-6455900/

Fans have created a fresh sequel to the 2006 3DS hit New Super Mario Bros., complete with 80 new stages spread over eight maps, some new gameplay mechanics, and an original soundtrack. The game was designed with a combo of new assets and assets from the original game.

The game, called Newer Super Mario Bros DS, was made by the group Newer Team. They created it using the level editor New Super Mario Bros. Editor (NSMBe), a PC tool released long before Super Mario Maker. Check out the launch trailer below.