This is rather a small suggestions, than a proposal for some feature!
Visible notification: Posts do not count!
This currently applies only for the Forum Games, but who knows what might change in the future,perhaps this rule will apply for some other forums as well. So I think it would be a fair to visibly point out that the posts do not count toward Posts-counter.
This would look like this:
I think this would be fair to the new users as well as the older users. It's always better when something like this is visible,and any possible misunderstanding would be avoided in advance.