Just a heads up, Windows flagged your file as a virus. Had to go into Windows Defender to bypass your game.
Took me a second to understand what was happening in the tutorial, but it was clear how the game worked after that. The art is super charming, I love how the map gets covered in splotches over time (including the ones from you dying). It's weird how the game doesn't tell you how many lines you get per stage, it's not a problem per se but it wouldn't hurt to give that information to the player.
I got through most of the puzzles with relative ease, but the one with the button that you need to pry open took me an embarrassing amount of time to get. I can't help but feel like I cheesed the HL2-sewer-puzzle-but-it's-a-ruler room, as I just stacked vertical lines without actually doing the puzzle.
All in all a very nice game, if you could port this to mobile you'd make bank but I can see it being difficult given the controls.