The latest nightly build lets you run your computer in extended mode, and after selecting the destination display, the drivers will automatically get your game to display on your HMD without requiring you to turn your main monitor off. It’s best to try and get your HMD and display to run at 75Hz.
Another experimental feature is Timewarp rendering which is a predictive technique for headtracking. You will get snappier performance in most games, but this can be turned off as well.
Finally, we added a Chromatic Abberation fix for DK2 users that can be toggled on and off. Have fun!