After first installing the game off Steam and launching it, it started a 1920x1200-pixel window.



Since those are user pixels (or whatever Apple calls them), a large chunk of the window was off the screen.



This is only a minor issue, because I could still get to the Options menu and change resolution or switch to full-screen, and after switching it, it remembers my choice.



However, after uninstalling the game, wiping out everything, and reinstalling, it again chose 1920x1200 on first run, so the problem seems to be repeatable.



Also, the options dialog goes all the way up to 2880x1800 in windowed mode. So clearly, your game is asking for the physical resolution rather than the virtual resolution, which it shouldn't be doing. Plus, it's failing to take into account the menu and title bar; it shouldn't even be offering to launch at 1680x1050 when that will mean 60-odd pixels fall off the bottom of the screen.



(If it isn't clear: A 15" Retina MacBook Pro has 2880x1800 physical pixels. The GPU renders to twice that, then scales down to the user's chosen resolution, which defaults to 1440x900, but there are four other choices, and I've set mine to 1680x1050. You can create an unscaled window and use native pixels, and your game does that in fullscreen mode, but in windowed mode it doesn't, so its 1920x1200 is 1920x1200 user pixels, which means 3200x2000 physical pixels, which is more than there are on the screen.)