Games happen to be classified in two different categories :

  • real time games
  • turn-based games

In turn-based games, the game lifetime is divided in steps called turns : the game iterates through turns until a winning condition is met.

Each turn players make decisions and perform actions in order to try and reach such a winning condition.

The time between two turns can vary from a few seconds to several weeks depending on the game.

Most board games are turn-based (chess, go, diplomacy, etc.).


The actors involved in a turn-based game are of two kinds :

  • player
  • moderator

The moderator is the entity responsible for handling the reference game state, computing game state changes and propagating those changes to the players.

As a side effect it should also check that players follow the game rules and of course do not cheat.

Computer games typically fall into two possible architectures :

  • Standalone : locally self-sufficient (player and moderator are different parts of the same application)
  • Distributed : splitted accross different locations (player application differs from moderator application)

Several ways to exchange data to perform distribution exist :

  • Network (e.g. connected)
  • Web (e.g. unconnected)
  • File
  • E-Mail

The architecture chosen mainly depends on how the players want to play (many games can work with several architectures), however the gameplay also has an influence (playing chess by christmas cards is not very convenient).


Game rules define how to handle player interactions and especially when those interactions can happen : the timeline of a turn often introduces synchronization needs depending on gameplay and game design.

A game synchronization mechanism can be anything from the lightest (any player can give any order at anytime) to the heaviest (at a given time only one player can take one specific decision concerning a given entity in the game).

Typical synchronizations are :

  • Free : no synchronization, not even at end turn (maybe turns are not even needed)
  • Parallel : players play simultaneously, synchronization occurs at end turn
  • Serial : players play one after another, synchronization occurs at each player end turn
  • Step : players play one after another, synchronization occurs after each player action
  • etc.

More likely synchronizations are implied by computation needs based on player actions in order to change the game state.

Some games may even mix several synchronization mechanisms.


DiplomacyParallel / Freeboard
JuntaParallel / Step / Freeboard
Heroes of Might and Magic IVStepstandalone / hot-seat
Battle Isle 4 - IncubationStepstandalone / email / local network / hot-seat
Spaceward'ho !Parallelstandalone / email / local network
Adventurer KingsParallelmail / email