Set Up Mechanics

What are Rules?

The Game Rules system is a visual scripting tool located in the Gameplay menu.

It allows you to set, use, and change values such as numbers, text, time, and true/false values for your gameplay needs and control what appears on the player HUD, or heads up display.

Launch Game Maker

• Open the Experience from the previous activity to reuse some of its logic.

Trigger: Joining the Game

Let's begin with a simple popup window that appears when a player enters the game:

Test

Press TAB to test. The popup window appears as soon as the Experience starts for you.

For now, let's set the Popup Window rule's Required Message to none so the window won't pop up every time we press TAB to enter the game and test logic.

Use a Text Variable in a Rule

Create a variable and a rule to use it:

Test

In a previous activity, the message Night is sent anytime the player enters an object's trigger volume. The banner will display the words "Banner Text," which is the value saved in the variable.

Overwrite a Text Variable and Reuse It

Let's create a message with arguments to send different text to the Rules System depending on where the player is located in the game world.

Now create a rule to overwrite the variable's text with the message argument:

Test

The banner rule doesn't use the text argument sent with the message, but still works. The rule to sets banner text uses the argument text included with the message.

Trigger: Keypress (to shoot projectiles)

Create a preset of the following asset. Delete the object after saving it as a preset.

Note: With these settings, the projectile will cause 100 damage if it hits an object that has the tag artifact, which was applied to objects in the previous activity.

Now create a pickable object with a child object that spawns the projectile preset:

Add a Key Input rule to trigger the projectile to spawn whenever a key is pressed:

Test

Press TAB to test. Pressing the 1 key shoots the projectile from the dragon egg anytime. Pick up your magical dragon egg with E and shoot all ancient artifact assets to collect the treasure!

Since an object that is picked up can’t send or receive messages in the current version of Game Maker, we created a child object to be the asset spawner. The projectile behavior triggers as soon as the object it’s applied to is spawned.

Count Resources with a Number Variable

Place the treasure preset from the last activity. Modify its collectable component so it will send a message to the Game Rules system whenever it is collected. Save this preset over the old version. Delete the object after saving it as a preset.

Modify all of the Ancient Artifact assets to drop the preset when destroyed:

Duplicate an Ancient Artifact asset until there are at least 20 in the game. Spread them out.

Create the following variable and rules to track and display money:

Test

Press TAB to test. Now as you destroy the ancient artifacts and collect the treasure that drops, you'll see the amount of treasure collected (100 per treasure). Each time you collect the treasure, which is a preset, you’re sending a message to a custom location.

In this case, it goes to All locations so it will reach the Rules system and increase your money when collected, which appears in the HUD slot you selected.

Make Variables Useful

Create an NPC to sell different types of items to players (equipment to wear, a consumable item, and a resource to be shown in the player HUD):

Create a preset object to spawn when purchased (delete after saving as a preset):

Create asset spawners for items to purchase and collect:

Add variables and rules for resources that will be tracked by number and displayed in the HUD:

Add a Shop rule preset to save time on the rest of the setup:

You already set up the Add Money, HUD, and Player Join rules earlier in this activity. You can remove the ones in this premade ruleset.

The remaining rules allow you to test if you have enough money to buy two types of items and pay from your money variable if you do have enough.

You have three items in your shop, so select and duplicate a Success, Fail, and Pay rule in this Ruleset to add what's needed for your third item.

Rename Item 1 rules "Purchase Food Success," "Purchase Food Fail," and "Pay Food." Rename Item 2 rules for equipment and item 3 rules for Wood to make it easier to track what each rule does in your custom setup.

Set the price of each item in the Success and Fail rules so it will check if you have enough and send a message if you don't, and use the same value in the "operand 2" value of the Pay rules to match and subtract an item's cost from your Money. Based on the number of treasures your game has, set food to cost 1, equipment to cost 4, and wood to cost 2, for example.

The messages sent by each rule matches the rest of the logic in the activity, but you can use custom messages to keep track of things more easily.

Finally, add a text variable and rule to inform players when they don't have enough money:

Test

If you destroyed some artifacts and collected treasure, you have money to spend with the merchant. You can set custom costs for each item in the Rules System and spawn any type of item you like or add resources for gameplay using variables.

Try opening your inventory to wear the equipment you purchased or consuming the food item that triggers a speed Power Up. The purpose of the items you buy are completely up to you.