Participants
Anybody who takes part in game activities to any degree is a participant. Exactly what your part in the game is determines what kind of participant you are.
Administrators
You'll generally interact with a handful of administrators at the beginning of the game when you check in, pay your dues, get your props inspected, and get your cabin assignment. Administrators, or just "admins," are involved in the business operations necessary to make the game run smoothly. When they're not performing their duties, they are players and plot members like everyone else.
Players
Most of the participants at an event will be players, paying customers who have come to spend the weekend as characters of their own creation. Don't miss the opportunity to interact with them in and out of play; it is a social game, after all.
Plot Members
Every good story needs its antagonists; in the Shards of Orn, they're called Plot. Plot members play powerful monsters and NPCs, orchestrate large-scale game events, and otherwise drive the story of the game and its players.
Marshals
Marshals are the game's referees. They enforce the rules and perform game functions such as issuing item tags, managing monster duty, and witnessing draws from the fate pool. If you ever have a question about a particular rule, you should ask a marshal.
Monsters
You will often see players roaming around in distinctive tabards initiating combat with other players. These are monsters. You can fight them or avoid them, at your discretion. With a few exceptions, every game participant must be a monster at some point during the event.