The platform physics were solid and the visuals were decent, but the controls felt really unintuitive. If everything is paused, why not let me move the mask with the arrow keys? Or put movement on WASD and have the mask be controlled by the mouse.
Unfortunately, there was more than one level where a key object like a button or a timer was almost completely hidden by the massive timer. I don't know if that was intentional, but it felt more like a frustrating oversight than a sneaky mechanic.
I also made the mistake of pressing Escape around level 2-3 or so - which immediately quit the game and erased all my progress, and the controls were too clunky for me to play it over again. Nevertheless, the fundamentals were very sound, and there's a big variety of levels.