I can only play this in small window.
Whenever I try to play in full screen, it lasts about 5-10 seconds and the game automatically minimizes itself to the task bar. I have to click there to reopen it, but it again only lasts 5-10 seconds.
I have Windows 10, modern CPU, 2080 Super Video card and other games play fine in full screen.
The demo must be glitched.