What is “trial-and-error”?
A “trial-and-error” course is one that forces the player to lose several lives while trying to learn what needs to be done. In a standard Mario Bros. level, you have time to look around and react according. Some creators in Mario Maker like to throw things at you where you can only avoid them if you know they’re coming. Basically, if you’re not the creator and not a mind reader, you’re going to lose a life. This will go on and on and on until you’ve died enough times to actually know the exact method for completing the course. This is unnecessary and time consuming, thus the reason we dislike these courses.