if you want to run the game at 1x1px, or 32x32px, or 1920x1080px, or something else entirely, that's all absolutely fine. if you want to include a button which changes the window size between some preset sizes, or toggles fullscreen, that's also fine. what would be against the spirit of the rules would be if the game changed the window size of its own accord, as a way to give the player more feedback.
