runscape is a well known game… i doubt if they got something to do with this.
it may be a fp, send avast a false positive sample-or in your case, tell them about the site (i will try to find the link if you want).
just to make it clear, its the adv, so there’s a chance that the company which’ve made this adv got something which isn’t legit.
just avoid this site for now, or download firefox and install the no-adv addon, and you won’t be disturbed by this issue.