What worked:
Sound design is really good. It's all balanced appropriately and adds to the game greatly. All the background things are fun and add a lot to the world the game takes place in. I sometimes would just watch the guards patrol so I could see what was there. The shortcuts are great and encourage the player to move just a bit further into the game after each death.
What didn't:
Light going through (and especially above) platforms, especially when avoiding guards. You have a significant health pool which is appreciated and mitigates this issue, but I'd take less health if I had more of a chance to avoid light entirely.
Good and Bad:
The player's movement feels clunky and sluggish, at first. After a few deaths (and reminding myself what genre this game is), the movement finally clicked for me. Since the guards are moving so fluidly, I at first thought of the game as a fluid kind of stealth game where the player runs and jumps around freely. Then I thought that it might work better as grid-based movement, before realizing that it already was grid-based. At this point, the disconnect resolved and I realized that I was a turn-based stealth character, facing real-time enemies. I really like this conceptually, plus it adds onto the lore of the game on the differences between the lurkers and the surface dwellers. The problem I have with it is how it's presented. It would serve the game well if you could figure out a way to present this idea to the player, so you don't enter the gameplay portion with a false idea of what you can and should do I think. Maybe some story, or some visual example? I don't know. I do think this disconnect is where the complaints about movement are coming from though.
Bugs:
Didn't see any.
Great job!