1. Open the Settings app.
  2. Go to System → Display → Graphics.
  3. Select Add Microsoft Store app in Add an app.
  4. In the Choose an app dialog and select GnollHack.
  5. GnollHack should appear in the list.
  6. Click GnollHack, which should open a list of options.
  7. Select High performance or Power Saving in GPU preference.