Well, I play ArmA 3 exclusivley with my Oculus Rift for hours sometimes and no problem there but handling weapons like in Onwards for example is for sure the missing part. Everything else is okay for a none exclusive VR title when you got all setup correctly like FOV and resolution for example. It's just that 3D is not 3D in ArmA like a true 3D enviroment, it's more like projected 3D when it comes to telling how far away objects are in front of you and is more dependant on the Z-buffer I guess