once game main menu has appeared and you can hear the music,
press the backtick ` key also known as tilde key ~, above Tab key on many keyboards.
you should see black screen with white line across it and a command prompt: >_
type:
setres 640x480 windowed
press Enter key
game should now be rendering in a 640x480 window so you should be able to reach settings icon to set your preferred resolution.
Another way is to find your Game.ini and set your resolutionx and resolutiony in there
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