re headtracking, use OPENTRACK https://github.com/opentrack/opentrack/releases to convert VR HMD yaw, pitch & roll to TrackIR which TDU supports natively.
Or you can
(1) buy https://edtrackerpro.mybigcommerce.com/
or
(2) build your own cheap headtracker with software and instructions from http://www.edtracker.org.uk/ and with an eBay or AliExpress sourced Arduino Compatible Pro Micro (ATMega 32U4) - 5V/16MHz and a 5 volt MPU-9250 sensor. (MPUs 9150 and non-magnetometer variant 6050 will also work) ***
Again, use OPENTRACK to convert the EDTRACKER 3-axis joystick output format to TrackIR format.
http://edtracker.co.uk/10-game-guides/26-edtracker-pro-opentrack
***
http://www.edtracker.org.uk/index.php/downloads/category/5-build-guides
http://www.edtracker.org.uk/index.php/downloads/category/5-build-guides?download=22:bartybee-s-bare-edtracker-build-guide
http://www.edtracker.org.uk/index.php/past-articles/11-news/72-using-the-mpu-9250
https://www.youtube.com/user/brumster100/videos
https://hobbycomponents.com/our-brand-exclusives/730-edtracker-diy-pcb
https://hobbycomponents.com/home/440-diy-head-tracker-bundle
Game works well in Nvidia 3D Vision, especially with an edTracker.
I tried it on my VR HMD, running the VR HMD as the primary display in extended multi-monitor mode (ie SteamVR Direct mode DISABLED; HMD is treated as just a generic monitor, not a special display device), using ReShade effects "SuperDepth3D" and "Polynomial Barrel Distortion for HMDs" https://github.com/BlueSkyDefender/Depth3D/tree/master/Shaders https://reshade.me/ https://github.com/crosire/reshade/releases , but is unstable as the d3d9.dll on TDUPE is custom and is overwritten by the also customised ReShade d3d9.dll - works fine if you use the original Atari TDU. Game is pretty flat (2D) though using ReShade Depth3D, but the car interiors work well.