Hands-On Usage
check_variable is most commonly used in scenarios involving tracking player-defined counters, resource variables, or progression stages—for example, determining whether an event chain has triggered a sufficient number of times, or verifying whether accumulated "prestige points" set via set_variable are enough to unlock a particular decision. The example below checks whether a country's "influence points" variable is greater than or equal to 50 before allowing a decision to trigger:
available = {
check_variable = {
var = my_mod_influence_points
value = 50
compare = greater_than_or_equals
}
}
Synergy
[has_variable](/wiki/trigger/has_variable): Check whether a variable has been initialized before using check_variable to avoid errors caused by missing variables.[set_variable](/wiki/effect/set_variable): Typically use set_variable in an effect block to write or reset variable values, then read and compare them in subsequent triggers using check_variable, forming a complete "write-read" cycle.[add_to_variable](/wiki/effect/add_to_variable): After performing cumulative operations on a variable, pair it with check_variable to detect whether a trigger condition has been met; this is the standard pattern for counter-based designs.[if](/wiki/trigger/if): Embed check_variable within if statements in complex conditional blocks to branch logic based on variable values.
Common Pitfalls
- Comparing variables without initialization: If the target variable has never been assigned a value via
set_variable or add_to_variable, check_variable will read it as 0, but in certain contexts this may silently fail or produce unexpected results. Always set default values in initialization events or on_startup and protect with has_variable checks.
- Writing comparison operators as assignment syntax: Beginners often confuse
compare = equals with assignment syntax in effect blocks, or mistakenly use = in shorthand forms to mean "equals comparison" (the correct shorthand for equality is { varname = 0 }), leading to logic that doesn't match intentions. Pay careful attention to the equivalence between shorthand and full forms.