Thanks for letting me know!
It's common for antivirus to flag game jam games & other small software because of signatures, especially if you're using Microsoft Defender. It's an unknown publisher so it's untrusted. The first time I downloaded it (my own game) from itch, I had to click "More info" and then "Run anyway", then it opened fine every subsequent time. There's likely similar options for whichever antivirus you use.
Obviously no worries if you don't want to do that. I plan to record & upload game footage at some point if you want to see it but don't want to risk opening the .exe :)
