I loved the demo! I've played it for so long now, it's very addictive. I have some constructive criticism:
> I think you should add more detailed information about how things work. Some mechanics are a little confusing. But you probably want to expand what's in the demo anyway. I'm excited for the full game!
> The English translation has many errors and sounds confusing sometimes, too. I understand this is an indie game and you may not have the resources to correct it, but if you can, please do. The game looks great and the translation can scare some potential players.
> Perhaps options to make the game easier or harder? Controlling how many enemies appear or something. But maybe explaining the necessary measures to contain enemies will be enough
In any case, keep up the good work :)