Extensive Form Design

For its experimental purpose and comparison with other types, see Game Types.

Extensive Form Design builds a decision tree directly from Player, Nature, and Payoff nodes. Layout is the main structural editor; Assignment supplies the available Players and Player Types.

Tree Layout with compact branches, Nature outcomes, information sets, and payoffs

The Layout toolbar provides undo, redo, display options, zoom controls, and commands for adding:

Player decision nodes,
Nature chance nodes,
Payoff terminal nodes.

The visible 100% value is tree-canvas zoom. It changes the diagram inside its viewport, not the overall application typography or panel size.

Nodes And Branches

A Player node belongs to a Player and presents labeled actions. A Nature node represents a non-player branch and uses configured outcomes or probabilities. A Payoff node ends a reached path and stores payoff formulas for the intended recipients.

Select a node or branch to edit it. The tree preserves branch order and lays complete subtrees out without crossing them when possible. Use zoom or fit controls for large trees rather than relying on browser zoom.

Information Sets

Information sets connect compatible Player decision nodes that represent the same observed situation. Nodes in one information set must offer a coherent action structure. The dashed connection in Layout identifies the grouping.

Use information sets only when the participant should not distinguish which connected node has been reached.

Assignment And Payoffs

Assignment distinguishes game Players from Player Types. Tree decisions refer to Players; runtime allocation maps participants according to Assignment.

Renaming a Player in Assignment updates all decision captions that inherit its name, including captions saved as that previous name. Independently authored node descriptions remain unchanged. Select the actor in a node when you need to change which Player acts there.

Each reachable terminal path should end in a Payoff node. Review every payoff recipient and formula after changing the tree structure.

Pre-Run Check

Confirm that:

the tree has one valid entry path,
every decision branch has a destination,
Player nodes use assigned Players,
Nature branches are valid,
information-set nodes are compatible,
every reachable terminal path has the intended payoffs,
Validation contains no errors.

For node creation, Nature edge syntax, information-set operations, tree display controls, and safe removal behavior, see Extensive Form Settings Reference.

Payoff labels

An empty payoff label displays the formula or value. Custom label text overrides that display. Label payoff independently shows or hides the player name; it does not set the custom label. Assignment changes preserve empty and custom labels. If an older game shows player names instead of values, inspect its saved payoff labels and clear unwanted text; an application update does not automatically erase custom labels.