Rules
Boardgame Lab uses a powerful visual scripting system that allows creating rules without writing any code. Rules can be attached to individual components (you can attach a rule to a card that determines what happens when that card is played, for example). They also describe the general flow of the game like what happens on a player’s turn.
Expressions
Rules consist of a number of expressions. An expression is something that produces a value. Expressions could be simple arithmetic operations or complex transformations on data coming from a property. For example, the following expression produces the value 3.
This expression is composed of a number of nested inner expressions (hover over the expression to see them highlighted). In order to evaluate the outer expression, the rule interpreter methodically replaces inner expressions with their values until the outer expression can be calculated.
Side Effects
Expressions may also contain actions that are performed on the board as the expression is evaluated.
Actions are also expressions even though they don’t really produce a value. They’re treated as expressions that produce an empty value.
Literals
Literals are the simplest types of expressions. They simply specify the value that they produce directly.