It can be anything. It could be something related to the forum's topic, or if you don't care about originality, the hugely popular Corrupt-A-Wish.;
, You don't want your thread to degenerate into spam, so having rules will hopefully keep posters on topic.
 Try not to do this while another similar, popular game is running. Make sure you are certain your idea is well received.
 Don't dominate the thread or spam/double post in an attempt to make it look more popular. Just play the game and enjoy it.
Think of an idea.
Get a set of rules written down.
Post your topic.
Participate.
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