The XU game is a freeform, forum based role playing game. Simply put, that means that you weave a story about super heroic mutants on the board in concert with the other players and moderators. The main objective of the game is always to have fun, and as such, there are very few rules. What rules there are will be mostly covered in this post.
The first and most important rule is to respect the characters of other players. Just as you would not like other players to put words or actions into the mouth of your character, give them the same courtesy. When describing an action that affects another player, post only your half of the action. Allow the other player to post the effect the action has on their character, and the reaction their character has to the event.
Example - Wrong:
Tom's Player: Tom shoots a telekinetic blast across the room, hitting James in the shoulder and knocking him down.
Example - Correct:
Tom's Player: Tom shoots a telekinetic blast across the room, focused on James' shoulder, with good but not perfect aim.
From this point, James' player can decide if the blast hits or not, and if so, if it knocks him down or not. He'll also post what James does next, and leave the reaction to, and effect of that up to Tom's player.
As you can see, this means that whenever you're in a contest with some other player's character, your opponent or competitor decides how much your character succeeds. This system works as long as everyone is willing to be honest, and reasonable. Remember, the game exists to create fun. So if you think your character would be unable to block a blow, stop a chess strategy, or chase someone through a rosebush, post that they have failed. If you think the character should succeed, especially in some area of specialty for them, go ahead and post the success.
Remember, no one will want to play with a character who is invulnerable and the best at everything. Give other players the chance to have their character shine, and they will give you the chance for yours to do so as well.
Formatting Posts:
The default way to format a post is to post descriptions and actions in regular text, without any modifications.
Example: Thomas walked into the room and waved to everyone there. Then he stopped and looked up, squinting at a spider on the ceiling.
Spoken words are enclosed in quotes, often with some text explaining who is talking, and how loudly, etc.
Example: Vicky called loudly from across the room, "What do you see up there?"
Thoughts are usually encased in italics. You don't have to post every thought your character has, just ones that you think might be interesting by way of narration, and thoughts that telepaths might pick up.
Thoughts that are projected or read via telepathy are italicized as normal, but also get quotes put around them.
Example: It's another one of those spiders, I've been seeing them everywhere.
Finally, when a player narrates a second character, such as a visiting friend or relative, a voice in their head, or an astral entity, the text is changed in color to indicate the second voice. This can also be used to indicate a character that is under some mind control or otherwise not in control of themselves.
Example: "It's nothing, don't worry about it." The voice came not from Thomas, but rather from somewhere nearby him...