This only applies to people who don't have windows aero enabled.

Like other games made with Unity TSFT uses only a borderless window mode, hence Vsync doesn't work. To enable real fullscreen mode, append "-window-mode exclusive" to the commandline of the games shortcut.

UPDATE:
After the recent patch the game uses exclusive fullscreen by default. If you want to change it back, just append "-window-mode borderless" to the commandline of the games shortcut.