> For the complete documentation index, see [llms.txt](https://kinematicsoup.gitbook.io/reactor/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kinematicsoup.gitbook.io/reactor/examples/timescaling.md).

# Changing Simulation Time

## Summary

Use Time.TimeScale to adjust server physics simulation times, or to stop the physics simulation from advancing.

## Description

Reactor server scripts can set the value of `Time.TimeScale` to change the rate of physics simulations and even pause physics updates by setting the time scale to zero. The default physics time step is based on the server frame rate, which at 60fps is 16.666ms. This value is then mulitplied by `Time.TimeScale` when advancing the physics simulation. The time simulated on each frame is tracked and synced to connected clients. Changing the time scale will change the value of `Time.Delta` on both the client and server. To get the unscaled time, use `Time.UnscaledDelta`.

The *ksRoomType* component has a property named 'Apply Server Time Scale' which can be used to couple the server timescale time with the Unity timescale. Enable this property if you want the Unity time scale to match the synced server time scale.

The following example code defines an RPC handler which will increase or decrease the time scale by a constant factor. Add this RPC method to a server room script and invoke `Room.CallRPC(0, true)` or `Room.CallRPC(0, false)` in a client room script to change the server time scaling.

*ServerRoomScript RPC Handler*

```c#
[ksRPC(0)]
public void ChangeTimeScale(ksIServerPlayer player, bool increase)
{
    if (increase && Time.TimeScale < 10.0f)
    {
        Time.TimeScale *= 1.25f;
        ksLog.Debug("Time scale = " + Time.TimeScale);
        return;
    }

    if (!increase && m_spawnRate > 0.1f)
    {
        Time.TimeScale /= 1.25f;
        ksLog.Debug("Time scale = " + Time.TimeScale);
        return;
    }
}
```

*ClientRoomScript RPC Call*

```c#
public void Update()
{
    // Increase the server time scale when 1 is pressed
    if (Input.GetKeyDown(KeyCode.Alpha1))
    {
        Room.CallRPC(0, true);
    }

    // Decrease the server time scale when 2 is pressed
    if (Input.GetKeyDown(KeyCode.Alpha2))
    {
        Room.CallRPC(0, false);
    }
}
```