Build Singleplayer & Multiplayer Logic

Use this one page guide to learn about Game Maker's logic systems and how they work together for single or multiplayer gameplay. Follow links as needed for more details in our documentation.

Game Maker's Logic Systems

Game Rules

Objectives (Quests)

Voxel Object Logic (Behaviours & Components)

Gameplay Parameters (affects all players)

GAME RULES

Rules are gameplay mechanics that can be triggered and completed repeatedly and use variables for all players or individual players.

Example: Points, Timers, Shops, and more

OBJECTIVES (QUESTS)

Quests are an individual player's progress in a singleplayer or multiplayer Experience's flow, which can be completed only one time.

Example: A quest to collect coins

OBJECT LOGIC

Behaviours & components are logic applied to voxel objects placed in the game world.

Example (image above):

Light, NFT Sensor, NFT Image Display, Play Sound & Trigger Volume This includes Spawn Point behavior, which includes unique settings per spawn point such as custom avatar, team assignment, equipment, tags, etc.

Gameplay Parameters

Global settings to customize basic interactions.

Example:

The player's avatar may be allowed to swim, breathe oxygen, receive fall damage, use abilitities, etc.

Object Logic

Logic Layers

[SP] & [MP] Behaviours and Components

A split between [SP] and [MP] logic was introduced with Game Maker 0.8.

This made it possible for players to experience some logic independently and other logic simultaneously with all other players. Synchronised logic includes position and state of objects, environment, global mechanics, etc.

An object may have one of the following logic setups:

No logic applied

Only [SP] logic "Client Only" - for each player to experience at different times Example: A player explores gameplay at their own pace and reads Quest dialogue when ready

Only [MP] logic "Networked" - for all players to experience at the same time Example: A door opening or a platform moving is synchronised for all players

In Singleplayer Experiences, [MP] logic works like [SP] logic. Gameplay design is more simple.

In Multiplayer Experiences, there are communication and bandwidth limitations to consider when designing gameplay.

Selecting SP or MP

Selecting [SP] or [MP]

1. Select an object and click on the behaviour or component field in the Properties panel.

2. When the pop-up window opens, use the dropdown at the top right to select a logic Type: All, [SP] Client Only, or [MP] Synchronised.

3. Click on the desired logic for your needs, and it will be added to the selected object.

There is no visual indicator in the viewport that an object has [SP] or [MP] logic. Select an object to view its properties.

Game Maker will automatically grey out options you cannot apply.

For example, [MP] and [SP] variants of behaviours and components cannot exist on the same object since they communicate on different layers.

Remove all logic to switch an object to the other type.

Trying to select a Behaviour or Component from an alternate network will result in the message: "BLOCKED BY Network policy incompatible with another behaviour/component assigned to the actor/s."

The message received when trying to add a [SP] Component to an actor with a [MP] Behaviour.

Triggering Logic Across Systems

Messages are sent between and within systems to trigger gameplay logic.

Logic can be a simple or complex chains of events, and it can be linear or branching with options.

There are many simple ways to send a message and trigger something to happen. Messages can also be directed more specifically using filters and tags.

Broadcast

Broadcast

Send a message on start of the Experience or when triggered, once or repeatedly.

Example:

• Add a Message Broadcaster behaviour to a logic actor or object and set desired parameters.

Use a message broadcaster as a middle step if two logic elements will not send or receive messages as quickly, consistently, or specifically as you want.

Detect

Object/Player Avatar Detection

An object can send a message when an expected tag is detected. It can also be set to play one of its animations. Detection is triggered when:

• player avatars are in range

• specific tags are in range

• specific objects are in range

Examples:

• Add a Speaker component and choose what to detect and detection range (avatars, tags, or a specific actor).

• To trigger an asset's animation and send a message when an avatar is detected or a message is received, use Animated Decoration behaviour.

• The Trigger Volume component can also detect and trigger a message when any tag enters or exits its volume.

Destroy

Object Destruction

Send a message or drop (spawn) a new object (e.g. loot, smaller enemies, etc) when an object is destroyed from an attack or an instant kill message.

Example (direct):

• Send Message - Add a Health component to the object that will be destroyed. Set a Message sent on death. You can trigger this with an Instant death message.

Example (indirect):

• Drop (spawn) object - Add a Drop component to the object that will be destroyed. Choose Behavior (default asset settings) or Preset (custom settings for one or more objects to spawn). Select the asset or preset to spawn.

  • Other objects nearby with a Speaker component can detect a tag that is included in your spawned object.

  • A spawned object, such as a Message Broadcaster, could instantly send a message.

Collect

Object Collection

Can be set as collectible by one player or every player, send a message, and/or play a sound.

Example:

Add a Collectable component to an object and set a message to send.

Interact

Object Interaction (E)

Press E to send the “Interact” Message. This can trigger a wide variety of events depending on logic setup.

Examples:

• Open a door to access a new area

• Toggle on/off logic

• Talk to NPCs for a quest

• Collect or pick up an item

• View NFT info (The Sandbox & external NFTs)

• More complex logic sequences

Quest

Objectives/Quests

Send a message after receiving confirmation that a quest condition is met and/or after the quest is complete.

Example:

• Create an Objective/Quest. In the Action After Completion dropdown, choose Send Message. Use the dropdown below this to select an existing message or create a new one. Any object in your Experience will be able to receive this message.

Rules

Game Rules

Most rules can optionally send a message when their logical flow is complete. Some may also be stopped or paused with a message.

Example:

• Add a rule to the gridboard, set the Message In, apply any custom settings you like, and set the Message Out. Trigger the Message In and the Message Out will quickly be sent.

Creating Experiences

👤 Singleplayer

1 Layer

One Layer of Logic

FULL DESIGN FLEXIBILITY

✅ [MP] and [SP] logic communicate with each other in singleplayer games.

✅ [MP] and [SP] logic communicate with an individual player's Objectives/quests.

✅ [MP] and [SP] logic communicate with Game Rules.

Fundamentals

[SP] means Client Only, and [MP] means Synchronised to all players. Both can be used in single and multiplayer Experiences.

Why use [MP] objects in a singleplayer game?

Some logic would cause conflicts between what is visible and what has collisions in a multiplayer Experience, so in some cases there is only a [MP] version available. [MP] logic works like [SP] logic in a singleplayer Experience.

Performance

[MP] logic DOES NOT reduce gameplay performance in singleplayer games compared to multiplayer games.

Variables (Game Rules)

Variables can track numbers, time, t/f states, etc. They can be applied to affect data for a player (P), team (T), or global (G) and change depending on player interactions. Global variables may perform slightly better in singleplayer Experiences.

Global, player, and team variables are unrelated to [SP] and [MP] differences. They can be used in a rule triggered by both types of logic.

Example: Part 1

Objective 1: Find the key and unlock the break room in 30 seconds

Game Ruleset: Countdown timer (triggered with Objective 1)

[MP] Objects: Pickable key, Door

Logic:

• The player picks up the key and takes it to the door.

• When the door detects the key nearby, it opens.

Example: Part 2

Objective 2: Get Seb a drink from the vending machine room

Ruleset: Shop (global or local variable for money)

[SP] Objects: Vending machine, Seb NPC, coin

Logic:

• Interact with Seb to trigger the quest and turn on quest markers.

• Collect enough coin objects (money variable in the Shop Ruleset) to buy a drink.

• Interact with the machine to get a drink.

• Return to Seb to give him the drink, which triggers the quest as complete.

👥 Multiplayer

There are two layers of logic that do not communicate with each other, but must be designed to feel seamlessly integrated for players.

Multiplayer Simulator

Toggle the Multiplayer Simulator at the top right in the Editor to test how the Experience will behave if published as singleplayer or multiplayer.

2 Layers

Two Layers of Logic

DESIGN RESTRICTIONS APPLY

❌ [MP] and [SP] logic DO NOT communicate with each other in multiplayer games.

❌ [MP] logic DOES NOT communicate with individual player Objectives/quests.

✅ [MP] and [SP] logic communicate with Game Rules.

Fundamentals

[SP] is Client Only for individual players and [MP] is Synchronised for all players. Both can be used in single and multiplayer Experiences.

Use Objectives for individual player goals. Use Crowd Events for collective goals.

Behaviours and components without [SP] or [MP] in the name are not compatible with multiplayer Experiences yet. They will be ported in the future.

Why use [SP] logic in a multiplayer game?

[SP] logic is necessary in the game world to trigger quests, which track each player's individual progression in your game. Some logic may also only be available as [SP].

Performance

[MP] logic should be used minimally in multiplayer games to add more gameplay potential without reducing the fun. Start by using as much [SP] logic as possible and then add the [MP] layer. You can build the same player experience that performs more efficiently!

Consistency

1️⃣ Consistent Type

An object with [MP] logic may only have other [MP] logic added. An object with [SP] logic may only have other [SP] logic added.

2️⃣ Consistent Messages

An object with [MP] logic may only send messages to objects with [MP] logic. An object with [SP] logic may only send messages to objects with [SP] logic.

3️⃣ Consistent Hierarchy

An object with [MP] logic may only be a parent or child of an object with [MP] logic. An object with [SP] logic may only be a parent or child of an object with [SP] logic.

4️⃣ Consistent Spawn

An object with [MP] logic may only spawn an object or preset with [MP] logic. An object with [SP] logic may only spawn an object or preset with [SP] logic.

Variables (Game Rules)

Use global (G), player (P), and team (T) variables depending on how you want number, text, and t/f values to be tracked and affected in your Experience. Learn more about How Variables are Applied.

Global, player, and team variables are unrelated to [SP] and [MP] differences. They can be used in a rule triggered by both types of logic.

Example: Part 1

See Multiplayer Logic below for more details on additional design considerations.

Objective 1 (auto trigger at start): Race to unlock the break room Gameplay: All players see the single player objective and rush to find the key

Ruleset: Countdown timer (triggered with Objective 1)

[MP] Objects: Pickable key, Door

Logic:

• One player picks up the key and takes it to the door.

• When the door detects the key nearby, it open for all players.

Example: Part 2

Objective 2: Get Seb a drink from the machine Gameplay: All players explore and find Seb on their own time, triggering logic only they can see.

Ruleset: Shop (Local variable - track each player's money)

[SP] Objects: Vending machine, Seb NPC; [MP] Object: Coin

Logic:

• Each player interacts with Seb to trigger dialogue, quest, and quest markers.

• Each player collects enough coin objects (money variable in the Shop Ruleset) to buy a drink (all coins must be [MP] and collectable by each player).

• Each player interacts with the machine to get a drink.

• Each player returns to interact with Seb to "give him the drink." A message is sent to Objectives to complete the quest.

Notes on Variable Types in Multiplayer

Using a player variable (P) The Shop Preset gives coins to only the players who trigger the rule to earn coins. It tracks this value as it changes (earning or spending) for every player individually. Using a global variable (G) The Shop Preset gives coins to all players even if only one player triggers earning them. It tracks this value as it changes (earning or spending).

Using a team variable (T) The Shop Preset gives coins to a team a player who triggers earning them is assigned to. It tracks this value as it changes (earning or spending) for the whole team.

Resources

• Experience Guide

• Quality Guidelines

• Game Production Guide

• Monetisation