Designing Games with Game Maker - YoYo Games

Check Collision
This is the reverse of the previous action. It returns true if there is a collision when the current
instance is placed at the given position (again, either only with solid objects or with all
objects).
Check Object
This question returns true if the instance placed at the indicate position meets an instance of
the indicated object.
Test Instance Count
You specify an object and a number. If the current number of instances of the object is equal
to the number the question returns true. Otherwise it returns false. You can also indicate that
the check should be whether the number of instances is smaller than the given value or larger
than the given value. This is typically used to check whether all instances of a particular type
are gone. This is often the moment to end a level or a game.
Test Chance
You specify the number of sides of a dice which is then thrown. Then if the dice lands on one,
the result is true and the next action is performed. This can be used to put an element of
randomness in your game. For example, in each step you can generate with a particular
chance a bomb or a change of direction. The larger the number of sides of the dice, the
smaller the chance. You can actually use real numbers. For example if you set the number of
sides to 1.5 the next action is performed two out of three times. Using a number smaller than
1 makes no sense.
Check Question
You specify a question. A dialog is shown to the player with a yes and a no button. The result
is true is the player answers yes.
Test Expression
This is the most general question action. You can enter an arbitrary expression. If the
expression evaluates to true (that is, a number larger or equal to 0.5) the next action is
performed. See below for more information on expressions.
Check Mouse
Returns true if the indicated mouse button is pressed. A standard use is in the step event. You