Table of Contents
Understanding Multiplayer in Roblox
Multiplayer in Roblox is about many players sharing the same game world at the same time. Roblox handles most of the low level networking for you. Your job as a designer and scripter is to decide which actions belong on the server, which belong on each player’s device, and how they stay in sync so that everyone sees the same important events.
In a multiplayer game, every player runs their own client. All these clients connect to one game server that hosts a copy of your place. When you build multiplayer mechanics, always think about how an action starts on a client, travels to the server, and then reaches other clients if needed. The rest of this chapter will focus on how Roblox helps you do this with RemoteEvents, the difference between server and client code, how to think about exploits, and how to keep players synchronized.
Important principle: The server is the authority. Clients should request or suggest actions, but the server decides what is actually allowed and what really happens.
Using RemoteEvents for Communication
RemoteEvents are the main tool Roblox gives you to let clients and the server talk to each other across the network. A RemoteEvent is an object, usually stored in ReplicatedStorage or inside a part or GUI, that can be fired from one side and listened to on the other.
There are two main directions. The client can send a message to the server, such as "this player clicked a button to buy an item" or "this player wants to swing a sword." The server can send a message to a specific client, such as "show this player their new coin count," or to all clients at once, such as "play an explosion effect at this position."
When you use RemoteEvents you must decide what data to send. For example, you might send a player reference, an item name, and a number. The network converts this into a packet and delivers it. RemoteEvents are not instant, but they are usually fast enough for most gameplay actions. You will learn the exact API when you focus on the dedicated chapter about RemoteEvents. For now, focus on their role as the bridge between client and server logic in a multiplayer game.
Rule: Use RemoteEvents to communicate between client and server. Do not try to access client-only objects directly from the server or server-only objects directly from the client.
Choosing Server vs Client Logic
Every piece of game logic must live either on the server or on a client. In Roblox, server code usually runs in Script objects, and client code usually runs in LocalScript objects. Multiplayer mechanics only work correctly if you choose the right side for each type of logic.
The server is responsible for anything that must be trusted, shared, or persistent. Health, currency, inventory, positions, and important game state should all be controlled or verified by the server. If one player defeats another, the server should decide whether that is valid and then update health and leaderboards. When a player collects a coin, the server should confirm they really touched it and then increase their coin count.
The client is responsible for what the local player sees and controls. Camera movement, input reading, local visual and sound effects, minor interface animations, and prediction effects are good examples. If a player hovers over a button and you want it to glow, the client can do that alone. If a user presses a key to swing a sword, the client should start the animation right away, then notify the server that the action happened.
You will often split a mechanic into both sides. For example, a shooting system might read mouse input on the client, send a RemoteEvent to the server with the shot information, let the server check hits and damage, and then notify all clients to show hit effects. Deciding this split is central to strong multiplayer design.
Guideline: Put authoritative game state and rules on the server. Put input handling and purely visual effects on the client.
Thinking About Exploits in Multiplayer
Because each player runs their own client, you cannot fully control what that client does. Some players may try to modify their client to cheat. They might attempt to give themselves more coins, more health, faster movement, or automatic hits. When you design multiplayer mechanics, always assume the client can lie.
You cannot trust values or decisions that come directly from the client. For example, if a client sends "I gained 1,000,000 coins," the server must not just accept it. Instead, the server should calculate coins based on events it knows about, such as valid coin pickups or completed quests. In the same way, if the client says "I hit this enemy," the server should check whether that hit makes sense, such as distance and timing.
Good multiplayer logic sends only what the client knows, such as input actions and positions, but never lets the client decide final outcomes. For example, the client can say "I pressed jump," but the server should handle gravity, physics, and check if the jump is allowed. The extra chapter about preventing exploits will focus on specific methods. Here, the important idea is to design mechanics that never require trusting unverified information from the client.
Rule: Never trust the client with anything valuable. Always validate important changes on the server.
Keeping Players Synchronized
Synchronization is about making sure all players see the same important events at roughly the same time. Roblox already replicates basic things for you. When a part in Workspace moves on the server, all clients will eventually see it move. When a character’s position or health changes on the server, every client will receive the updated information.
For more advanced mechanics, you may need to combine this automatic replication with RemoteEvents. For example, if you spawn a special effect, you might create it on the server in Workspace so that all players see it through normal replication. For small, local-only visuals, such as a hit marker on your own screen, you can spawn it only on the local client. If something must appear at the same time for everyone, such as a countdown or round start announcement, the server should be the one to start it and notify all clients, either by changing shared state or by broadcasting a RemoteEvent.
Network delay means that actions will not arrive at the exact same moment for every player. Multiplayer mechanics should be designed with this in mind. Instead of relying on exact timing down to a tiny fraction of a second, design systems that work with slight differences. For example, a round timer can be controlled by the server and each client shows its own copy of the timer based on server messages. The numbers might not be perfectly identical at all times, but they will stay close enough for fair play.
Key idea: Let the server drive shared events, and let clients display and smooth those events so that the experience feels consistent.
Designing Fair and Responsive Multiplayer Systems
Strong multiplayer mechanics feel fair and responsive at the same time. Fairness requires that the server controls important outcomes the same way for everyone. Responsiveness requires that the client reacts instantly to the player’s input, even before the server replies.
To combine these, you often use prediction and correction. The client can predict what the server will say, such as starting an animation immediately when the player clicks, then adjust if the server later disagrees. For example, if a player shoots and misses, the client might briefly show the shot as if it could hit. When the server responds with the true result, the client shows the hit or miss effect. If the server rejects the action completely, the client can quietly cancel or adjust it.
Design your mechanics so that small corrections do not feel strange. If a player tries to move too fast due to lag, the server can place them back to a valid position. If you have a race, the server should decide the winner based on its own time records, even if one client believed it finished slightly earlier. Visuals should always support the server’s decisions rather than conflict with them.
As you create more complex systems, always ask two questions. First, what part of this system must be trusted and the same for everyone. Second, what part can be handled locally just for player comfort and visuals. The answers to these questions will guide how you use RemoteEvents, how you divide logic between server and client, how you defend against exploits, and how you keep your players in sync in every multiplayer experience you build.