The central concept here is very interesting, and all sorts of intricacies emerge as you draw the line. The puzzles are increasingly complex, and very clever.
Unfortunately, the control scheme was a bit fiddly; frequently, when trying to draw I would just drop my character off the screen (even through solid platforms).
Also, room puzzle games like this always benefit from a Retry button! (Yes, in most cases the player can just reset the level by falling off a platform, but sometimes the player character will be trapped by a line and unable to reach the edge until the line decays.)