UNPLAYABLE ON 3440x1440p monitor. 1920x1080p is the highest supported resolution. You can force it to full-screen but then the top and bottom visuals are off-screen. On my 3440x1440p monitor, this is unplayable unless it's played in windowed mode in a tiny 1080p box. There are steam threads showing the devs were requested 2-3 years ago to add ultra-wide support and they never have.