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Show a transparent desktop game

Before you start​

Complete Installation. Run a Win64 package or a separate Standalone Game with -DGTStandalonePreview.

Use a camera looking at a mesh or sprite with empty space around it. For sky and clouds, enable Holdout; check the fog limitation in the same section. Floors and opaque full-screen widgets can cover the desktop.

Set up startup​

Create a Player Controller Blueprint, assign it in your active Game Mode > Player Controller Class, and build this flow in its Event Graph. Keep existing BeginPlay/EndPlay logic when using an existing controller.

  1. Add a Boolean DesktopSetupComplete, initially false, and a custom event TryDesktopSetup.
  2. On BeginPlay, get the Desktop Game Window Subsystem and bind On Desktop Window Status Changed to a handler that calls TryDesktopSetup. Then check Get Desktop Toggle Hotkey immediately. If true, reuse the existing session binding and mark setup complete without changing modes; this handles map changes. Otherwise call TryDesktopSetup immediately.
  3. In TryDesktopSetup, stop if setup is complete. Check Get Desktop Window Status for Interactive, ClickThrough, or RestartRequired, then require Get Current Display to return true. Other statuses do not run setup; shutdown also emits status changes.
  4. Call Set Desktop Toggle Hotkey: Key Z, Ctrl true, Alt true, Shift false. Check Return Value with Switch on EDGTResult. Only Success continues to Set Desktop Presentation Mode: Transparent.
  5. Set DesktopSetupComplete true only after presentation returns Success. On either failure, read Get Last Desktop Window Error and show its message. Keep the guard false so an explicit retry can call TryDesktopSetup again after changing the chord.
  6. On EndPlay, unbind your own status handler. Compile and run.
Loading Blueprint…

Use Print String for development feedback and visible game UI for Shipping errors. Ctrl + Alt + Z is an example binding; another application may already own it.

Expected result​

The game opens Opaque, then shows the desktop through clear pixels after setup succeeds. Press Ctrl + Alt + Z to toggle Interactive / ClickThrough. The shortcut does not toggle transparency.

Each new launch requires registration again. Continue with Hotkeys, window controls, or display selection.