Yeah I already checked for false positives and also contacted Notion Games. What I've found out from forum topics on Avast is that an advertisement seems to be generating the problem, but I cannot confirm anything at this point since I still can't visit the page. Hopefully someone will be able to look into it.
Try white-listing tracking cookies... Those are pretty harmless, and you can get rid of them by clearing out your cookie cache right after you leave the site.