Fix: GameMaker Room Creation Code Runs Before Instances

Room creation code tries to set Player.hp = 100; Player doesn’t exist yet so the assignment errors.

Execution Order

1) Room transition starts. 2) Room Creation Code runs. 3) Each placed instance’s Create event runs. 4) Room Start events on instances. Trying to find instances in step 2 fails.

Use Room Start on a Controller

// On an obj_RoomManager Room Start event
with (obj_Player) hp = 100;

Room Start runs after all Create events. Instances exist; you can reference them.

instance_create_layer in Creation Code

If you spawn instances in Creation Code (instance_create_layer), they exist by the time you reference them — just don’t expect placed instances yet.

Persistent Manager

A persistent obj_GameManager whose Step or Other > User Event handles per-room init reliably. Doesn’t depend on Creation Code timing.

Verifying

Per-room setup runs after all instances exist. References resolve; init values apply correctly.

“Creation Code is too early. Move init to Room Start on a controller instance.”

Reserve Creation Code for setting room properties (background, view bounds); put gameplay init on a manager’s Room Start.