Ah, I had just now realised that the main character is an eyeball XD
Your game is very sensitive to sudden movements of the mouse, making me have to readjust my position ever so often; sometimes, when I stop moving, the character suddenly aims at a slightly different angle, making me miss my shots :p
Anyhow, I noticed that in your patch notes that there is a 4th entity, but I've only encountered 3 forms of the boss (normal-sized black entity, room full of dust balls, and an enraged gigantic black entity with bleeding eyes).
I find that while I can see the dust balls, sometimes I end up touching the 3rd form quite a bit as it's silhoutte is not visible, or that it's hitbox is quite big.
Other than that, pressing space bar to continue the text at the end tends to make the webpage scroll down, which would be the same problem your Spiderbite game previously had. Also, I've had to minimise my browser's zoom just so that I could comfortably play this game without having any blindspots, and your background is still a little dark (though I can see why you went with it, since the main character is an eyeball :) )
P.S.: Did you change the game just now? Previously after beating the first phase, I would have a score of 80, but now I start with 0 :o
I'm using the Firefox browser by the way
I can't really reliably fix the sensitivity of the aiming, but I can make the background brighter! It appears html5 resets the blend coefficient of all active objects to 0, but the problem is easily fixable and the solution will be presented in the next patch.
As for the fourth phase/entity, I may have been a little unclear. The first phase has two movement sets. When you begin, the boss is on a track going around the outside edges of the room, shooting at you. After you reduce his health by half, his moveset changes and he begins to actively follow you. I counted this as a phase, but it's more like a bit of a small shift in the first phase. Sorry if that was a bit confusing. :)
As for the space bar, I'll fix that the same way I did in Spiderbite: changing the button used in the next patch.
Thanks again for your bug spotting! :)