Hi, I just finished the Demo. It took me two hours, and well over half of that was owed to the boss.
What you made so far is looking great, I appreciate the many options such as custom sharpness to the pixels. All the particle effects (I hope that's what they are, I'm not really a dev myself) look really good, such as when you fire and when you vaporize small enemies. The sound effects are quite nice too, especially the enemy sounds. The ambient music is nice, but a bit of a short loop.
What I'm missing is the ability to shoot straight down and up when hanging from a ledge. It seemed to me that using the triggers might be used for that, like when you're in the air. Also, it's weird how you lose a tad of momentum when landing from a jump. Oh, and the screen tearing is unfortunate since V-sync does add a bit of input delay. But good on you that you put that warning on the option, since I would not have noticed it otherwise.
Now, the boss is a real killer. As I died a few times, I felt myself getting better at it and stuff that I thought I was going to complain about seems fine in retroperspective.
There are a couple of things though: I started crawling to avoid the super-quick overhead dive the Slither does, but I found myself getting hit three times by it anyway only when all of its eyes were gone. I might just have crawled a pixel too far to the edge, but I'm unsure so I mention it regardless.
And then there are the flies. Oh man, the flies. The varying distances they come out at sometimes meant that I would miss one because it barely ducked under my shot, and I'd get hit. Also the screen going all grey when you get to low health made me straight up not see them when I was looking out for the bright purple boss, resulting in the flies killing me. It's rough when you get hit by an unlucky fly and get ten energy or nothing at all in return. Or when you then jump in to collect the energy and immediatly get bodyslammed by the boss coming up the middle. By the way, do sometimes more flies spawn than normal? I think I was facing down ten one time.
But what gnawed on me more than the boss or the flies (pun sadly not intended, it was one of my better ones) was the way back to the boss room from the save point. Might there be a possibility for some sort of soft checkpoint outside of the room for when you die to the boss only?
You wrote that you unlocked all doors after the boss, but I found myself unable to go anywhere new except for the charge beam in the adjacent room. All the colorless doors are still locked. I thought I might be able to return to the starting area with the green door, but I couldn't jump up at the point where you get the Geo Suit. Did I miss something newly explorable?
And here's something that just happened as I'm writing this: when I tried to start up the .exe a second time, it didn't work. I opened task manager and found it just running as a background process, loafing around at 0% CPU usage. Killing it and trying again sadly does nothing different. I'm currently playing on Windows 10, if you want to know.
The characterization of our protagonist so far is minimal, and that is quite alright. Not that I'm saying I don't want her to have any character, but in this regard one can overdo it.
The environments are great and quite detailed. I like the glowing green spikes in subterra, and all the havoc caused in the facility. Of course the purple slime is a highlight in being so dynamic and truly looks goopy. It's good to see that the underwater stuff doesn't slow you to a slugs pace and make it a chore that way.I think that's finally everything I wanted to say. I'm stoked to see what further things you'll do with Zordak. And thank you for what you've made and shared with us so far.