Do you know how, in a lot of RPG's, there is an attribute system, where certain types of attacks are strong or weak to certain types of enemies? For example, how, in Pokemon, there are electric type pokemon who are strong against water type ones who are strong against fire type ones who are weak against rock type ones and so on, or how in Bakugan there's light which goes against darkness which goes against water and so on?

That is how this game will work; à la the stonecutter parable, every post will invent an attribute that is strong against the one someone posted before it. You also must explain why it's strong against it.

Example:
Poster 1: Caterpillar
Poster 2: Bird
Poster 3: Windstorm
Poster 4: Boulder

First person gets to choose the first attribute.

Poop.

Fox News

Presumably being made of it grants innate immunity.

Memory.

A solid one is both armor and sword against any 'news' mill.

Time.
Stackable effects lead to greater Memory losses. When the Time passed exceeds the importance of a Memory, said Memory is lost.

Entropy

Heat is work, and work's a curse / But all the heat in the universe / 
Is gonna cooool DOWN.