Those who want to be a part of or participate, chose a comic book character, or create one of your own, or take a pre-existing comic book character and alter him to your preferance, but remember their will be no one super power above everyone else, those will be NPC's. Beyonder, Phoenix, Spectre and such will be allowed but do not expect them to remain all powerful thus dwarfing everyone else.
The story will revolve around a plot, the characters will be those you and anyone else who participates picks, their actions, personalities and choices will be influenced by your posting style, content, and in some cases decided by you or the characters player directly.
Example:
Stark staggers in the crimson soaked hallway, with every step taken the puddles of wine beneath him deepen, black smears streak across his body and face; charcoaled fragments of his once radiant armor incinerate to ash before his very eyes. As all begins to fade and as tears of ice fall to the obscure shadows below so fades the spark of the golden avenger.
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Then Ironman or whoever may be involved at the time decides what they are to do (and they would also decide what they did during the battle prior, what happened prior to Ironman is not listed but its an example), the dialogue and choices will also be based and decided on the players.
Battles will also be between players, for instance Ironman and Namor fight, both players will list what they desire to do to defeat or purposely lose or etc. to the enemy, friend, etc. I will then write a description and story for the battle.
So the story will be in a way directly influenced by the players, and your post on other threads will also be a factor in your characters choices, outcome and actions.