Thought you had to have at least g+ to sign up. I just signed up through my gmail account and I can now post in those articles. Do you have a gmail account because it seemed pretty damn easy that way?
edit- I just tried to post twice and it doesn't seem to even post (it posts but then when I go back the post is gone). Is there a review process or something? I usually just ignored those gmrReview articles because you should be able to post from your VGC account. I only post in VGC articles and usually ignore gamrReview articles. So fuck it. I won't ever try to sign in again under disqus to post in the article nor will I ever log into that other site they made which took our game database (ability to add recent games).
second edit - it now shows the post in a refresh.
