Designing Games with Game Maker - YoYo Games

Here you select the event you want to add. Sometimes a menu pops up with extra choices.
Here is a description of the various events. (Again remember that you normally use only a few
of them.)
Create event
This event happens when an instance of the object is created. It is normally used to set the
instance in motion and/or to set certain variables for the instance.
Destroy event
This event happens when the instance is destroyed. To be precise, it happens just before it is
destroyed, so the instance does still exist when the event is executed! Most of the time this
event is not used but you can for example use it to change the score or to create some other
object.
Alarm events
Each instance has 12 alarm clocks. You can set these alarm clocks using certain actions (see
next chapter). The alarm clock then ticks down until it reaches 0 at which moment the alarm
event is generated. To indicate the actions for a given alarm clock, you first need to select it in
the menu. Alarm clocks are very useful. You can use them to let certain things happen from
time to time. For example a monster can change its direction of motion every 20 steps. (In
such cases one of the actions in the event must set the alarm clock again.)
Step events
The step event happens every step of the game. Here you can put actions that need to be
executed continuously. For example, if one object should follow another, here you can adapt
the direction of motion towards the object we are following. Be careful with this event though.
Don't put many complicated actions in the step event of objects of which there are many
instances. This might slow the game down. To be more precise, there are three different step
events. Normally you only need the default one. But using the menu you can also select the
begin step event and the end step event. The begin step event is executed at the beginning of
each step, before any other events take place. The normal step event is executed just before