The reason antivirus programs flag some Unity DLLs is because of heuristic detection. It doesn't actually mean the game contains a virus, but since it's an unknown program without a digital signature, Windows and some antivirus engines tend to be suspicious of it.
If you look at VirusTotal, 11 out of 66 engines flag it, and most of those detections are just generic Trojan labels. If it were a real virus, you'd likely see something much closer to 66/66, or at least a much higher detection rate.
You can even search Google for "Unity Build Files Flagged as Malware" and you'll find plenty of cases like this. I'm not asking you to trust it blindly, I completely understand that it can sound like a risk that isn't worth taking.
As soon as I can afford to digitally sign my software, I plan to do so. It's just not cheap, and that's one of the reasons I'm currently saving up for it. :)







