So, I loved this demo, great concept with great execution. There were a few things that I found frustrating however, such as the diagonal shooting. I understand that the player is supposed to figure a lot of things out on their own, but assigning the diagonal shooting mechanic to a button, and not telling the player about it felt agitating. Maybe put a hint text on the item when you obtain it, or some additional controls related to the item?
There are a few things that I did love however, such as how there are different types of water, and each had negative effects, but in different ways, such as how the beginning water takes away oxygen, and later water pools take away energy. Also, I didn't know if it was a bug or not, but occasionally when I would shoot at a crawling bug enemy, they would stop, wait a second, then flip over. It gave me the impression that the creatures were just as scared of the player as the player was as scared of them. Another nice thing is that the secrets were designed in a way that made me want to start shooting around to find out if there were any other secrets. It felt natural and rewarding.
Overall, loved it, and I look forward to a full release. Keep up the good work.