Interesting take on the theme, you start with basic size changing then go on to manipulating the light to control the scale of the shadows.
Not a bad and fairly polished idea, but there are a few critical bugs.
On the forth screen, moving the light source to certain spots just killed the player for seemingly no reason. And later on, at the screen after the ramp with spikes on it I got stuck in a perpetual loop of dying after a fall, pressing r didn't help either.
Overall some sort of in-game tutorial would go a long way. I didn't even know I could control the proximity of the light source via the scroll wheel until I checked your theme explanation whilst writing this comment. Which now I know makes a lot more sense in regards to how the game fits the theme.
Also as ironic as it is being a game about shadows, I think the game could be a little brighter overall, it was hard on my low brightness screen to see the character and obstacles when they weren't directly in the light.
But regardless of my nit-picks, good job on completing this submission.