Try updating DirectX, hopefully that'll fix the issue.
Recent community posts
Many of the demo's features were added to the recent WHITE VANILLA update, so demo isn't essential as a prologue. However in terms of gameplay it still offers somewhat different, if less refined experience so feel free to give it a go if you're interested!
We ultimately came to a decision that a new, more distinct name would go a long way in helping with the game's recognizability now that we're making a commercial release. "Final boss" wasn't exactly google-friendly for people trying to find information about the game after all.