i7 4th generation, 16GB, GTX980 4GB,
ACER windows mixed realtiy HMD

installed windows mixed reality 
installed Steam for Windows mixed reality

installed VorpX, Desktop Viewer (not free)
Steam App – BigScreen (not free)
Cliffhouse Store – BigScreen (for free)
Cliffhouse App – Desktop

Warthunder installation direct from WarThunder page
Warthunder installation from Steam

playing VR using WarThunder and set launcher the option VR
Attention:
if VorpX gets activ everything is messed up..
you have to go into VorpX settings and add process aces.exe, is not enough to add  file launcher.exe , to do that you have to start the launcher, start game and hit Windows key to go back to desktop and into VorpX settings to exclude files/processes, aces.exe will be listed and you can pick this up and exclude

playing WarThunder in VR means playing max 90fps.. that the max fps value the HMD can reach.. we dont need to waste power to calculate more frames per second as realy needed..

Tryed to play Warthunder 2D(VR option disabled) in VorpX, but that did never work.

Playing WarThunder in VR/3D works
BUT
pros:
– nice cockpit view(very close distance objects)  and nice look around feeling in first person view
– nice third person view too
contra:
– not realy playable, because far objects are not realy visible, close objects/planes are not that detailed as expected/wished
– problems using mouse, sometimes the mouse pointer is where? and plane stays in vertical position…
– locked to 75 fps ..why? even with all possible options set to low, never acchieved 90fps
– looking vertical down, the ground isnt moving smoove, instead its making little steps/jumps.. you see that effect if you fly near the ground

Playing WarThunder in 2D works
using Cliffhouse desktop app
– before prepare, set desktop fullHD 100 fps (i setup even 90 to match max HMD fps, but in game appeared 100 again..)
– set thunder launcher the option Vsync on (gaphic card can reach over 200fps if Vsync is off)
– steering works as like as always used to
– we can setup a virtual screen size a big as wanted and look into corner hud infos via head movement

Next try
play war thunder first person view in 2D (realistic and simulator),
using hmd movement to steer the in game first person view!
so we need to lock/disable/disconnect the hmd movement related to the virtual screen
– this works not in Cliffhouse desktop app
– this works not with App BigScreen (Steam and Windows MixedRealtiy App)
This works only with VorpX Desktop Viewer…
– pro:  it works, but you need to setup Hostas/Joystick to control the plane and use mouse for View because HMD movement is used as mouse inside the game, its not differentiated
– contra: you never can see the hud infos in the corners! you see only clear in the center, that could be better if the game could run in 4:3, or 1:1, in 1440×1440 desktop size.. i did not achieved yet, setting VorpX desktop viewer to 4:3 only squeezes the 16:9 into 4:3

best graphic quality we have in 2D Cliffhouse Desktop App (and BigScreen app, and VorpX Deskop Viewer) … when we use HMD to look around infront of the bigscreen, to see/reach even the hud information in the corners, and play input devices as used to without extra configuration…
the 2D first person option fails because of the not reachable hud information in the corners..

NEW discovered impressive new 2D version:
 i used VorpX Desktop Viewer, 
the key is the VorpX Mode: Sphere + Vertikal 90 + Horizontal 150
this spans the 16:9 Desktop as a round shape infront of us,
from left to front to right side…
as effect we see a 4:3 viewport straight infront.. and use HMD head movement to reach the sides left and right
starting war thunder in 2D…
we see nice clear view…
flying inside cockpit view is very good…
fly with hostas/joystick,
to look at wings left and right, and look around over shoulders.. i can use mouselook-button, i have configured mouse right button, press and hold this i can use mouse AND headset movement to steer the lookaround, releasing the rightmouse button goes back to looking frontside..
now i have to map that rightmouse button action (mouse lookaround)  to another button at the joystick…so that i can activat and release this HMD steered looking around feature easily..
with that now.. we can play the WarThunder Realistic Mode
and EVEN BETTER the Full Simulation mode, which only allows cockpit view for all gamers!!!
dont forget VorpX ambilight..

this concept could work in the App BigScreen too, where we can have a Sphere/curved screen in front of us.. using HMD for look around, look to left&right side..
and remember on windows, the app BigScreen is for free

UPDATE:  BigScreen kann die Leinwand fix vor den Augen halten. Option nennt sich „Move Screen“
„““To make this work, click on „Move Screen“ under Customize Screen Settings (The Screen Icon), click and hold, „Move Screen“, then drag your cursor/laser pointer away from the button. After that, just close your tablet and your screen will be locked to your head.“““

UPDATE: Desktop custom Auflösung 1080×1080 100fps nutzen um die Grafik an die quadratischen VR Displays anzupassen und die HUD Informationen besser positioniert/sichtbar zu haben.

Nachteil:  WarThunder kann offenbar bisher im Standard 2D Modus keine Headtracking Informationen des WMR Headsets benutzen.. und man muss eine extra Headtracker Lösung benutzen. Vielleicht kann Gaijin das noch nachliefern.