A megagame is a type of large-scale simulation which can contain elements of role-playing games, tabletop games, LARPing and wargaming - the amount of these is dependant on the scenario being played and the way the players choose to engage with the scenario. Participants can be arranged into hierarchies of teams - some games will consist of multiple competing factions and others will have teams operating in different game 'niches'. Megagames have been played with up to 300 people, though are more usually played with 30-80 players. The term was coined around 1980 by the wargamer and historian Andy Callan, and developed into a game system by military theorist and historian Paddy Griffith.
"A Megagame is a multi-player game, in which, usually the participants are organised into teams, and those teams into an hierarchy of teams"
An organisation called Chestnut Lodge Wargame Group, based in South London, ran games similar to modern megagames throughout the late 1970s, but the first game ran that was called a megagame was Memphis Mangler in April 1982. The game, written by Griffith, was a Vietnam wargame with about 30 players. Megagames were popularised in gaming communities by a video of the first run of the Watch The Skies megagame in May 2014.
Megagames cover subjects such as modern and historical military conflicts, political scenarios, Machiavellian historical drama, science fiction and fantasy genres.
A megagame will take place over a number of turns which can represent time intervals ranging from days to months depending on the scenario being played. Each turn can be broken down into phases again depending on the scenario. These phases can consist of:
- Team time, where the team must stay together at their table to discuss their approach to later phases and update each other with their progress during the turn.
- An orders phase, where map players will move and/or place units to reflect their attempts to influence the map state.
- A meeting phase, where the appropriate team members can meet with other teams in order to try to influence them.
A game might consist of a 'adjustable' number of turns to create a level of uncertainty and to reduce the likelihood teams or players attempting 'extreme' actions in the last turn. For example a game could be scheduled to run for 8-10 turns, with the final turn being declared at the end of one of those turns.
The games are moderated by members of Control (or referees), who perform a similar role to that of the dungeon master in a traditional roleplaying game. It is their job to react to the actions players attempt to take during the game. Megagames of between 50-60 will include 5-10 Control players - the largest Watch the Skies megagame had about fifty moderators for 300 players.
In large megagames specialist Control roles may be needed to facilitate specific aspects of the game mechanics. In some scenario or plot based theme Plot Control will help manage the various storylines that may have been seeded by the original setting, or have been created by players during the game. In most games where maps are used to represent the locations involved Map Control will coordinate the activity of players and non player factions on each map and help resolved the outcome of conflict if needed. Overall Game Control will oversee the game as it unfolds and deal with escalations and major plot elements if they are an aspect of the game concerned.
Winning and losing
In most scenarios winners and losers are not determined - the players can judge for themselves as to how well they have performed within the game they have played and can judge their outcome against team and personal objectives. Operational megagames may well have victory conditions that can be achieved. The general aim of a megagame will be the group generation of multiple responses to the scenario and starting conditions in the game. In general the end result of a megagame is the stories created by the players at the end of the game.
There are a couple of main formats of megagames.
Operational Megagames are typically military what if scenarios and will include an extensive and detailed rule set to reflect the capability of forces and equipment that might be found in the era the game is set in. There is little room for improvisation around the rules and players will be expected to operate closely within the game mechanics.
Standard megagames, like Watch the Skies, will have a light rule set and there is large scope for improvisation and suggesting plans to Control, who will moderate of the potential for those plans to succeed based on the game scenario and the level of rationale that the players can provide. Other games may have mechanics for political states, economic and trade mechanics and in some games they can include a science side game which may benefit the players teams if they invest in those options.
Watch The Skies
The awareness of megagames within gaming communities grew following the original run of Jim Wallman's Watch The Skies megagame on 17th May 2014. The game was filmed by board game reviewers Shut Up & Sit Down and then shared on their website. They then followed up with a further documentary on a large version of Watch the Skies 
In the game teams of three to six players represent nations of the world reacting to the arrival of an alien race. Players take on diplomatic and military roles in their dealings with other teams, the room being divided into separate tables for each country, and others for a world map or the United Nations and alien team(s). In some versions corporate entities will also be added to the player teams. Much of the gameplay comes from the players reacting to the unfolding events and actions of the different teams in the scenario. The game has been compared to a Model United Nations activity "but there are aliens and everyone has all these tanks, itching for a fight".
Watch The Skies remains the most popular megagame in the world, having been run on every continent. Several different variations exist, including Jim Wallman's original design, his updated "Lite" design and a design by the MegaGame Society of New York.
In July 2017, Jim Wallman ran Urban Nightmare: State of Chaos, the first Wide Area Megagame, taking place simultaneously in 11 different locations in Europe and North America. The game setting was a zombie outbreak across America, with each physical location representing a different state. Over 600 players took part.
The megagame God Emperor has a pseudo-historical setting, and some similaries to a worker placement boardgame, where teams face each other across three smaller, interlinked games covering war, politics, and espionage, and must decide each turn where to send its five players.
There is a growing community around Megagaming, with organisations appearing around the world.
In the UK
Last Turn Madness <ref>https://soundcloud.com/last-turn-madness<ref>
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- "The explosive growth of the 300-person "megagame"". Ars Technica. 17 September 2016.
- "SU&SD Play… A Goddamn Megagame » Shut Up & Sit Down". www.shutupandsitdown.com. Retrieved 2018-07-10.
- "Megagame Society". megagamesociety.com. Retrieved 2018-07-10.
- "Urban Nightmare: State of Chaos Megagame Review - BeckyBecky Blogs". BeckyBecky Blogs. 2017-07-12. Retrieved 2018-07-10.