(Keep them in the main forum)
Why?-The fact that they might not be as noticeable or active. It better suits the main forum so that way new and upcoming members that join the "Random guild" have some fun entertainment to look forward too. I just feel that if it were to have its own sub-forum it won't be attracted to much attention, and some of these fun forum games/discussion are very entertaining for the main forum. So why take the risk of it being unnoticeable? How ever the decision is up to you.