I would have liked the RAR download. But as a desktop browser game, I will ditto that it is clean, the controls are responsive (there's even an odd "cling" mechanic not described).
The lighting is neat, but in the ultimate/penultimate puzzle it does play a trick with the right-most square (with a spike sticking out) - at least with my eyes, the square looked orange enough, but when lit looked yellow. (If that was an intentional "look-carefully" trap, it was very subtly done.)
One critique I have is that rebounding from spikes/damage feels inconsistent. Sometimes I get trapped bouncing vertically on the spikes in the left wall and have to move left/toward the wall to get bounced out.
Also, what's up with the ending? It feels like a "missing asset/under construction" terminus. Is there just the one?