Hey I just got done with the game and I managed to solve the puzzles and get the 2 necessary keys and open the door and end the demo. First things first I think the game looks cool and the music is pleasant. I think the padlock puzzle where you get the silver key can be easily missed. Those symbols on the ground could probably be harder to notice for some people.
The gooey hand I think it was called I managed to figure out how to use it. But the area where you have to use it to get the final piece of the gold key I discovered mainly on accident. I saw those marks on the ground and used the gooey hand there and solved that puzzle but it wasn't exactly clear that you should use the gooey hand in that way. Other than that I enjoyed this short demo and I think the concept is interesting and can easily hook players from the get-go. I should also mention I haven't come across any bugs or visual glitches. Overall this was a great experience.