Wow right off the bat the style of this game is dialed up to 11 and that's not even discussing the amazing mechanics!
I was immediately sucked in by the opening sequence. Very old school spy / James Bond style opening sequence that was beautifully animated and match to the audio. An absolute treat that sets the tone of the game perfectly.
The potion/light mechanics of the game are so fun and interesting and I love the process of creating your own safety areas with your potions and the light. Then the introduction of the black potions that took it away to create holes, perfect combination.
The art was great, I loved the negative space styling of the main character and the simple yet effective means of using the light/dark to communicate space and objects.
Although I mentioned it previously the audio is great throughout with no misses in music or SFX.
I got badly stuck on the last level (not counting the random arrow/drop level at the end) where my dark potions kept interfering with my light ones trying to get past the wall near the door. The dark ones would just completely overwrite the light ones even if the light from the light potions should still be seen. This also happened at the start of the level trying to get through the initial wall. I ended up throwing the light potion up and over the wall instead of trying to throw it through the hole I made or throwing it mid-air.
I suspect that was probably your intended solution which is why I had such trouble doing anything else but the final jump of the level was really difficult because of the way they interacted with each other.
Also I wish I could throw more than 1 potion at a time. I'm assuming it's designed that way intentionally but still I wish I could do that.
Overall it was a great experience and full of style and love. My only real complaint is that I want more. Give me more!