# forceSingleInstance

> Restrict standalone players to a single concurrent running instance.

## Definition

* **Type:** Property
* **Namespace:** [UnityEditor](/engine/6000.7/script-reference/unityeditor.md)
* **Assembly:** UnityEditor.CoreModule

```csharp
public static bool forceSingleInstance { get; set; }
```

### Remarks

This detects at startup whether another instance of the same player is already running, and aborts with an error message if so.