You can use it at any resolution on any display. That's the draw.
not sure if you can select any resolution. the settings give multipliers. So eg 1.2x, 1.5x, 1.78x, 2x. Can't remember exactly how many there were but not that many.
And sometimes even if you've clicked all of those, the higher resolutions don't show up in game - the game has to support the higher res I think.