Rules Summary

This page is not intended to replace the Callisto rulebook – which is available as Pay What You Want from DriveThruRPG. Instead it is meant to act as a quick reference for players of the game.

Callisto is a play-by-mail game based on the olden days back when we played by actual mail. Yes we actually sent pieces of paper with writing on them (hand writing, almost always) through the post with our orders on them and some poor sod collated them and sent back responses.

See also: Setting tenets, Movement tenets, and Army and Fleet tenets.

General Rules

There are three types of e-mails that a player may send and one which the referee will send. They are:

  • Communications (Players)
  • Movement orders (Players)
  • Rule queries (Players)
  • News updates (Referee)

Communication e-mails

Play is conducted via players exchanging e-mails with the other players they have the contact details for. These e-mail represent letters, e-mails, and other similar communications between characters.

All such communications must also be CC’d to the referee so that they are aware of what is happening

Typically starting characters will only know the contact details for other characters they are likely to have encountered in their lives. Meeting new characters is accomplished either via an introduction from a mutual contact, or from being in the same location so the characters can meet up. In addition, the referee may, at their discretion, introduce two characters – usually to prevent the game slowing down.

Communication Etiquette

  • Do not send e-mails to people not on your contact list.
  • Do not CC a bunch of characters into the same message unless you are introducing them – use BCC instead but always remember to CC the referee.
  • Assert action in your communications. Use “I have dispatched my daughter as ambassador” instead of “Would it be OK to send my daughter to you?”.
  • Please use a consistent subject line tag of “[Hush]”. This way people can filter, sort, file, and tag their e-mail.
  • Players may never communicate with each other out of character except to clarify existing communication: you cannot strategise about the game rules in email with each other. You can certainly bargain about character actions but you cannot explain how you will manipulate the rules with each other.


Players are restricted to sending three (3) communication e-mails per week. In case of confusion, weeks will run Monday to Sunday – and there should be no penalty for players who are unable or unwilling to send all there e-mails in a given week. We are all busy people with busy lives and this is just a game.

On a rough level, each of these messages covers a week of in game time and some actions will take time to achieve which will be measured in messages rather than exact in-character times. Each planet/system tends to have its own method of tracking and delineating time – feel free to invent your own calendar for your starting world and add them to the description of the world.

Movement e-mails

Movement e-mails should be sent to the referee and should simply consist of the details of which map hex they wish to move – following the Movement tenets.

Rule Queries

These should be sent to the referee who will adjudicate the outcome/answer.

News updates

Based on the contents of the letters, the referee will post news updates to keep all players informed of major updates to the setting. These updates will be based on the areas of Narrative Authority that the players control.

News updates will be e-mailed to everyone, and also archived in the Adventure Log on this Obsidian Portal page.

Narrative Authority

Each of the players will be given one or more areas of the narrative they are allowed to control. When their character makes a statement about matters related to this area that statement is true. These areas of control are related in some fashion to the type of things the character is involved in – but crucially not over the area of the narrative that would allow the player to simply achieve their own character’s goal.

The referee will update all the players as to the new truth via the medium of news updates (which may take a myriad of in-character forms: newspapers; TV broadcasts; radio interviews; etc).

Rules Summary

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