Game Life Cycle

Elements on this page refer to the file structure, concepts, and API of an Empirica experiment.

Empirica experiments are event driven. The image below summarizes the lifecycle from the beginning of a game through exit steps.

Beginning and intro steps

In the admin panel, you would create a Batch of games for players to join. Players enter the game where they go through a consent form (optional), they provide an identifier (which can be set via URL queries), and they do the intro steps (the instructions and other components you have set in the intro steps. All of these are set by you in the ./client . During these steps, players are asynchronous; namely, they complete these steps at their own pace until they have finished them, independent from the pace of other players.

gameInit

Once players finish the intro steps they are sent to a lobby where they wait until every player has joined. When every player has joined, the Game object is created based on what is set in ./server/main.js in the Empirica.gameInit() . This is where certain parameters are set, and where the Rounds and their Stages are created.

In the ./server/callbacks.js, Empirica.onGameStart() is also triggered at the same time as Empirica.gameInit(). Any pre-game preparations can be done in either gameInit or onGameStart interchangeably. It might make sense to the Game designer to split the overall mandatory Game configuration (Rounds and Stages) in gameInit, from data initialization (using set on Game, Players, Rounds and Stages objects) in onGameStart, but it is not required.

Rounds and Stages

Then players go through each Stage of each Round. Once a Stage is finished, they move on to the next. If this was the last Stage of a Round, they move on to the next Round. If this was the last Round, they move on to the Exit Steps.

During these steps, players are synchronous; namely, every player has to finish each stage before they can all move on to the next.

In the ./server/callbacks.js, a series of callbacks are triggered during this process:

Game end and exit steps

Finally, when the last Round ends, after the end of Stage and Round callbacks are triggered, the onGameEnd callback is called in the ./server/callbacks.js.

After which, the players goes through the exit steps. During these steps, players are asynchronous; namely, they complete these steps at their own pace until they have finished them, independent from the pace of other players.

List of callbacks

The list of callbacks goes as follows in order:

  • gameInit Required

  • onGameStart

  • onRoundStart Repeated for each Round

  • onStageStart Repeated for each Stage

  • onStageEnd Repeated for each Stage

  • onRoundEnd Repeated for each Round

  • onGameEnd