I do not know why Windows is flagging the game as a virus for you. This is something I take very seriously. I have scanned all demo files, as well as my development files, and have not found any virus. I even re-downloaded the game from itch and scanned that - nothing. This leads me to believe that there may be something else on your system that is infecting VolleyShot.
I highly recommend downloading a trusted third party virus protection suite and performing a full scan of your system. Let me know if this helps!