Your first Reflex module

A Reflex module has two sides:

• scripts/main.lua runs on the player’s client;
• scripts/server.lua runs in that player’s server context.

They expose different API sets and exchange Lua tables through Network.

Note

Only one Reflex module can be active at a time. Use a regular module for HUD, UI, and any other fully local behavior.

1. Create the project

1. Open the module menu and select Create.
2. Name the module HelloReflex.
3. Enable Is Reflex.
4. Confirm creation and select this Reflex module as active.
5. Start a custom game session.

The project directory should contain both entry points:

HelloReflex/
├── module.json
└── scripts/
    ├── main.lua
    └── server.lua

2. Add the client code

Open scripts/main.lua:

scripts/main.lua

Network:OnTableReceived(function(data)
    if data.kind == "server_tick" then
        print("Server tick: " .. tostring(data.tick))
    end
end)

Network:SendTable({
    kind = "get_server_tick"
})

The client registers its response handler and then sends a request to the server side of the same module.

3. Add the server code

Open scripts/server.lua:

scripts/server.lua

Network:OnTableReceived(function(data)
    if data.kind == "get_server_tick" then
        Network:SendTable({
            kind = "server_tick",
            tick = Time.Tick
        })
    end
end)

The server checks the message type and sends its current tick back. Once both sides are loaded, the client console shows Server tick: ....

If no response appears immediately after hot reload, save main.lua once more. The client request must be sent after the server side is ready.

API contexts

Do not move client code into server.lua without checking the reference.

Capability	main.lua	server.lua
ImGui, UI, Cameras	✅	❌
Scheduler:OnFrame()	✅	❌
Scheduler:OnTick()	❌	✅
Network	✅	✅
Server game API methods	Limited	✅

API pages mark client and server members separately.

Data supported by Network

Strings, numbers, booleans, and nested Lua tables can be sent. Functions and API objects such as Agent or Vector3 are not serialized.

Send compound values as numbers:

Network:SendTable({
    position = {
        x = position.x,
        y = position.y,
        z = position.z
    }
})

Server-logic rules

• check a message-type field such as kind;
• validate the range and meaning of every client value;
• do not trust data merely because it arrived through Network;
• do not call client APIs from server.lua;
• use Scheduler:OnTick() for repeating server work.

Continue with Network, Scheduler, and the reference pages for the game objects you need.