Oh wow, what a review! Thank you so much for putting all of that effort in! I'll be sure to try your game tomorrow and give it a really proper review too.
For the aesthetics, I actually started out making a couple of different generations of sprites and it just looked like the worst thing you can imagine. After trying to rework it a bunch of times I experimented a little bit with making honeycomb patterns, which just gave me the idea of using actual 3D cubes in Unity to make my them come alive, which also meant I didn't need to try using Blender again (there not many programs I just don't get, but that's one of them), and it became this kind of pixel-art style but using 3D cubes, which I agree just worked so well, so that was a lucky one! I had already spent way too much time on it, and it was millimeters away from ending up just a green mess because I had to move on and make the actual game. And the HUD placement actually came out of the controls, because I tried to make it control with the absolute position of the mouse at first, but then changed it to relative, so the cursor just had to follow player around, and I also think it totally worked - it would have felt very strange do something else, but I might have if I didn't start with the cursor.
I'm happy you also notice the rage mechanics, because I was worried they wouldn't really come across at all. I wish I would have had more time to put into the level design, and also that I was much better it to really give you the opportunities to do all the cool moves that should be possible. But I think the reason you didn't really get a feel for it is completely my fault. I've been thinking more about the controls, and I think what would probably make the most sense would be to use the thumbstick on a controller to control the player (and maybe the second thumbstick to control the camera). And, since I went a bit all-in on the effects, I even get the occasional lag spikes on my i7 6770k, GTX 1080 rig...! There just wasn't time to do anything about it. The explosions shouldn't be able to send you back into a previous section though, since the doors are already closed (unless you had used the reset button (space bar) - that one also resets the doors!). In future versions I'll make sure that won't happen for any reason though. If the game is not fun then it's my fault and I want to fix it! :)
You know, I figured an intro is more fun than a menu, and it takes like 45 minutes to implement it with a simple animation (you can make so many quick and dirty things like that using the animation tool in Unity, it's great! Just copy the world, remove all components from the player and other stuff you want to animate, and the just drag stuff around with recording on).
Thank you so much for this huge effort you put into both trying and analyzing my game, and also for taking the time to communicate it all to me. Expect one in return tomorrow!