Thanks for your interest in Dash Dodge! A preview mode is a good idea in the level editor, as it will be much easier to build levels to share with your friends. I will add this feature in an upcoming update!
Thanks for your interest in Dodge Dash! I like the idea of the up/down movement, so I'll probably add some levels in a future update! As for the level editor, I'm not that advanced at programming, but I'll give it a go, and it might be in a future update too!