The ASTEROIDES DRM and the "system" that verifies its originality within STEAM can result as a "troian" for some antivirus.
All DRM protected games simply access the internet to verify their originality and not to allow copying.
We are working to fix this, we have sent the executables to rule out the problem. In any case, when asked to run ASTEROIDES, confirm it without problems.
the bit ManiaX
https://help.steampowered.com/it/faqs/view/1F39-DCB4-FF28-5748