What's a Family in Construct 3?

A group of object types sharing common behaviors and variables. EnemyFamily might include Goblin, Orc, Troll — all sharing ‘hp’ family instance variable. Events can act on the family generically.

Why does reading a family var get the wrong value?

Construct picks one instance from the family when you reference it in expressions. Without a picking condition (e.g., ‘On collision’), you might get an arbitrary instance. Use ‘For each’ or compare conditions to narrow the selection.

Can I read a specific family member's var?

Pick the instance first (by collision, comparison, UID). Then EnemyFamily.hp refers to the picked instance. Use System -> Pick by Unique ID with EnemyFamily.UID to target a specific one.

Fix: Construct 3 Family Instance Variable Not Readable

Quick answer: Construct picks an arbitrary family member if no condition narrows the selection. Use For each or condition-based picking before referencing a family instance variable.

A wave-defense game has an EnemyFamily containing Goblin, Orc, Troll, all sharing an hp variable. An event reads EnemyFamily.hp expecting the current enemy, but the value belongs to a random instance.

Picking Selects an Instance

Construct’s event system uses “picking” — events filter which instances apply. Without a picking condition, expressions can return any instance’s value, often the first.

Fix: For Each

Wrap iteration in For each:

Add “System → For each EnemyFamily”.
Inside that block, EnemyFamily.hp refers to the current iteration’s instance.

For each EnemyFamily
    EnemyFamily.hp < 0
        → EnemyFamily.Destroy

For each runs the sub-events per family member, so picks are scoped to one instance at a time.

Fix: Conditional Pick

For specific instances, pick via condition:

On collision EnemyFamily with Player
    → Subtract 10 from EnemyFamily.hp

The collision condition picks the colliding enemy. EnemyFamily.hp in actions refers to it.

Pick by UID

If you stored a UID earlier and want to act on the same instance later:

System → Pick EnemyFamily by UID stored_uid
    → Set EnemyFamily.hp to 100

Useful for callbacks where the instance reference must persist (timers, async events).

Verifying

Debug overlay: print EnemyFamily.hp inside For each. Each frame shows the iteration order — verify each instance’s hp changes independently. Without For each, expect arbitrary single value.

“Pick first, read second. Family vars without picking are random reads.”

Construct’s picking is the engine’s superpower — once you internalize it, family-based architecture is incredibly clean.