Press Z to go to level editor. In editor, press 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, A, and B to place blocks. And 0 is for removing. Arrow keys to move grid space. You can also go really fast by holding an arrow key. Green flag to test your level. If you want to create a new level then reload the site.
all i did was remix the project "新・ボールころころ4" and did nothing else.
