Really liked the mechanics, it's simple but elegant. The levels are difficult without being impossible and I like how the game teaches mechanics with gameplay. It's satisfying to beat a level. I do think the difficulty should go up a bit slower. The difficulty ramps up fast in the first couple levels and evens out. Would be nice also to see some small UI changes like a "next level" button rather than right click, a win screen at the end of the game, and effects when you collect items, open doors, or die.
It could make a great mobile games with more levels, I was just getting into it when the game ended. Good game!