This looks cool, but be careful if you plan on publishing it. Projects that violate copyright or use material belonging to someone else (in this case Mario belongs to Nintendo) often get taken down. Modifying the built in samples is a great way to get better at SmileBASIC though!
As MathPRG said, uploading it carries the risk of getting the project taken down and can even get you banned from instant publishing or even banned from uploading at all.
Of course, you can still modify any built-in/downloaded programs for learning purposes or personal use. Just make sure not to upload them.
