Activators are State Connections that connect two nodes. They activate or inhibit their target node based on the state of their source node and a specific condition. The activator's label specifies this condition. Conditions are written as an arithmetic expression (for example '==0', '<3', '>=4' or '!=2') or a range of values (for example '3-6'). If the state of the source node meets this condition then the target node is activated (it can Fire). When the condition is not met the target node is inhibited (it cannot fire).
Activators are used to model many different game mechanics. For example, in the board game Caylus players place their laborers (a resource) at particular buildings on the board to enable them to execute special actions associated with that building. For example, a player might place a laborer at a goldmine in order to collect gold (see diagram below). However, as indicated by the trigger this diagram, in Caylus every time a player exercise this option, the laborer is returned to the player's laborer pool.