Hi, Yeah, we are aware of that issue and trying to figure out how to fix it. The purpose of this demo is to see if the contents are okay and to check how buggy the game is(so that we can fix it). The black screen bug may be related to the direction of the game folder. If your direction has symbols or signs like !@#$%^&*(()_+ \|, the game won't strat properly. Thank you for letting us know about the bug.
And for the optimization, we forgot to add a frame limit to the game, so the you get like a few thousand FPS and that makes the game so buggy laggy and shitty.