Ok so I love the idea, and the environment is sick as hell I was instantly intrigued/invested in this world and already starting thinking what this giant rainbow prism meant, and why I'm sucking light out of these crystals. However, there are a lot of gameplay issues. The crystals shoot too often and have too large of a range, their SFX also gets annoying pretty fast because I can still hear it even if I'm far away. If you're low health and try to suck the light, it's very difficult because the crystals nearby will still try to attack you so it's a lost cause, so you just go to the crystal, die trying stealing the light, respawn and rinse and repeat. Perhaps you can give the player immunity while getting light, or don't spawn crystals till you've sucked all the light, so the player will have a chance.
Anyways I wish you'd spend more time ironing out the gameplay because I would like to spent more time in this world.