Rune has issues when alt-tabbing or playing in windowed mode on modern systems. These can be easily fixed by making the following edits to the Rune.ini configuration file.
By default, the windowed mode in Rune uses a different renderer than the fullscreen mode. This can cause crashes when alt-tabbing and graphical issues when playing in windowed mode. Changing the windowed mode renderer in the Rune.ini to match the fullscreen mode renderer should fix both issues.
It's recommended you first install the updated graphics renderers before making these changes. Follow our guide on How to Install Updated Renderers for Rune.
Windowed Mode Fix
In the Rune/System/ folder, open Rune.ini in a text editor and make the following changes to your rune config. Find your game's current renderer setting on the line starting with: GameRenderDevice= then copy the value of that renderer to the line starting with: WindowedRenderDevice=
Under Config Section: [Engine.Engine]
Find Text: WindowedRenderDevice=SoftDrv.SoftwareRenderDevice
Replace With:
WindowedRenderDevice=D3DDrv.D3DRenderDevice
or WindowedRenderDevice=D3D9Drv.D3D9RenderDevice
or WindowedRenderDevice=D3D10Drv.D3D10RenderDevice
or WindowedRenderDevice=OpenGLDrv.OpenGLRenderDevice
Startup in Windowed Mode (Optional)
To enable windowed mode on start up, edit the following settings in your Rune.ini:
Under Config Section: [WinDrv.WindowsClient]
Find Text: StartupFullscreen=True
Replace With: StartupFullscreen=False
Other Issues
Windows 10 settings may also cause crashing when alt-tabbing. See the guide How to Fix Rune Windows 10 Issues and Crashes.