absolutely phenomenal demo, I can't wait to see where this project goes next. The aesthetics were beautiful and charming, and the puzzles were fun.
The controls are a bit clunky, but that's to be expected from a demo. It would be quite nice to be able to use keyboard controls to switch between interact and look, and to have a way to walk a little faster (such as a simple sprint toggle)
The elevator section, though very fun. was a little confusing and took a while to get used to, and might have overstayed its welcome a little bit with how long the bar took to fill up. It also had some bugs, but they've been mentioned countless times in the other comments. Its difficulty was also slightly too high for the last phase, but that has also been said by others. I loved the way the boss looks during each of the phases.
It was a little confusing to have a way to save manually in the first section that doesn't actually work (on the computer), and then no actual way to manually save in a specific save slot (at least, that I could see)
One issue I had is that for me, using multiple variants of wine on linux, the game starts with an absolutely tiny window size, where almost nothing is legible. I had to guess around until I stumbled upon a higher resolution size.
Slightly related to the previous point, I wanted to play on a lower resolution to emulate the retro feel of the game, but that was made difficult by the text on objects and the in-game PC in the first section, which is very hard to read at lower resolutions. I do know that rendering texts at lower resolutions can be a pain, though, so I can't see a good solution for this.
I really can't overstate how much I love the artstyle, music, voice acting and everything relating to the art direction. Apart from a few minor hiccups in the gameplay side, it was a really enjoyable experience and I'll be looking forward to future releases.
edit: formatting and some more point