I too had the same issue. When I started the game, it was not using the maximum resolution available. Navigated to Options > Video. Resolution was blank. Selected resolution and changed it to 2560 x1440. Fullscreen mode was now stretched horizontally and my cursor was drawn a good 200 px to the right and about 30-40 px above where I was actually selecting. Could not drag my mouse far enough to the right to select the options without navigating outside the game window. Restart did not help. redtj2's workaround worked. Since I could not deselect fullscreen, hitting f11 brought it to windowed, where I was able to reselect my resolution of 2560 x1440, and then hit f11 again. Cursor is now aligned properly.