How to Enter Play Mode Instantly in Unity

How to Enter Play Mode Instantly in Unity

When entering Play Mode in Unity, you may have noticed a loading progress bar appearing for a few seconds before the actual execution begins. This occurs because Unity reinitializes scripts and reloads the scene every time. During rapid iteration or frequent testing, this waiting time can become quite inconvenient.

How to Enter Play Mode Instantly in Unity

To address this, you can go to Edit > Project Settings > Enter Play Mode Settings and disable both Reload Domain and Reload Scene. By turning off these options, Unity skips the initialization process, allowing you to enter Play Mode almost instantly. This can be extremely useful when you want to quickly verify small changes or behaviors.

How to Enter Play Mode Instantly in Unity

Reload Domain

In Unity, the term Domain refers to the AppDomain in .NET — the runtime environment in which C# scripts are executed. By default, Unity creates a fresh AppDomain when entering Play Mode, which resets all static variables, singleton instances, and event subscriptions. This ensures that each play session starts from a clean slate.

However, when you disable Reload Domain, Unity skips recreating the runtime, meaning all static variables and singletons retain their previous state. This can lead to unexpected behaviors, such as duplicated event calls or incorrect game logic that relies on fresh values.

How to Prevent Issues

To safely use this feature, it’s important to explicitly define initialization logic. For instance, if you are using static variables, it’s a good practice to create a dedicated reset method like the example below: 

public static class GameState
{
    public static int Score;

    public static void Reset()
    {
        Score = 0;
    }
}

Then, make sure to call this method whenever Play Mode starts. For singleton classes, having a dedicated ResetState() method helps ensure proper cleanup and a consistent state at runtime.

Reload Scene

Disabling the Reload Scene option prevents Unity from reloading the current scene when entering Play Mode. It might seem like the changes made during Play Mode persist, but in reality, Unity still restores the scene to the version saved in the editor once Play Mode ends. That means any changes made during Play Mode are temporary.

This can be misleading if you're expecting persistent state, so it’s important to understand that “not reloading the scene” doesn’t mean “saving scene changes.” It simply avoids discarding and reloading objects in memory, which slightly improves performance.

Conclusion

Turning off Reload Domain and Reload Scene can dramatically speed up your workflow, especially when you're rapidly iterating or testing minor changes. However, if you overlook proper initialization, even a small mistake can result in elusive bugs.

If you plan to use these options, make sure your project has a clear and reliable initialization structure from the beginning. With careful setup, you can enjoy faster testing without sacrificing stability.

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