Super Mario Maker is an upcoming Wii U game that lets players custom-make their own Super Mario Bros. stages. Nintendo shared the latest look at its many possibilities in a new trailer shown during their E3 2015 Digital Event.
As shown in the video, courses are easy to make, and can get pretty chaotic by doing things like having Bowser show up in stage 1-1. Similar to custom-made Super Mario Bros. games on the Internet, you can pretty much have obstacles and monsters show up any way you desire.
Super Mario Maker will release in September 11, 2015 for Wii U.