Cool twist on the drawing game formula, that impressively demonstrates that less is more. I really love how the "only one line"-limitation can turn an innocent looking level into something very complex, but still allows for more than one solution, thus player creativity. I would say the level order is a bit random, but that's totally understandable. I found it really difficult too to judge the difficulty of my own levels. Certainly would be easier to play with a touch interface than with a mouse though.
My game: https://njamster.itch.io/wonkey (playable in browser, not mobile friendly)