When I first launched the game (on Steam) it kept flashing between resolutions on my 3440 x 1440 monitor, settling on a small 1920 x 1080 image. Each time it changed, the game lost focus and I couldn't click in a field to type in my Dovetail Live login. This made it impossible to start the game by logging in. I had to create a fake profile without Dovetail Live and then start the introduction before I actually could change the resolution. Easy solution: Make the settings menu accessible from all screens.
