interesting, so this is something like BMOUSE that makes DN3D more enjoyable... will give it a spin ! thanks!

Thank you for your interest, Keropi.

This is basically a tool that makes a wheel mouse pretend it's a VR headset from the 90s (plus whatever manipulator that came with it) thanks to an API Raven have added for those.
I have not researched Duke 3D, but did a quick search for similar Heretic tools after posting and there is one called RAVMOUSE. I have examined the thread on DoomWorld about it and the author has pointed out a limitation: after respawn or starting a new level, game engine's and driver's "head pitch" diverge. So there's now synchronization via the said API's built in method in the latest build, but the players need to trigger it manually (bound to RMB tripple click).

Also made it easier to start the game with the driver, using batch file provided.

Have not tested CUTEHT with Hexen, albeit it also has a similar (if not same) API - need to check the game source code first.

*UPD:* Added Doom support. For Doom -d argument is to be given, and only turning/strafing/firing/using are supported as well as weapon selection with mouse wheel and middle mouse button press. A bit of an "academic interest" thing, but it was fun to add this and I used it for testing "newly restored" external driver support in BUCK/Krapfen Doom (which is the DOS source port I develop on from time to time).
The downloads in this very post have been updated.

Since I was not entirely content with how free mouse look felt in Heretic, I did couple more tweaks to the driver.
- added an option to apply sensitivity in a "non-linear" fashion
- made vertical look feel smoother

In fact, the latter was not exactly a driver change. Modifying vertical look angle in 5-unit multiples was a limitation of the game itself, and I could not resist modding the .EXE to change that to 1 or 2 units. In the attached package, SMOOTHER.BAT runs a patched version of HERETIC.EXE (v1.3 is expected) and also configures the driver to take advantage of this.

Enjoy.

Using higher sensitivity with mouse-driven horizontal turning has brought to light (or should I say "to sound") strange behavior in Heretic around how stereo separation is being applied to sound samples. When player is turning fast enough clicks start to be heard if a positional sound source is playing nearby. This can become quite annoying, especially when using headphones, but limiting "stereo swing" (reducing the range of possible separation values) removes the effect at the expense of making stereo effect in the game less "pronounced".

The patch to HERETIC.EXE (v1.3) is available in the attachment along with JPATCHT needed to apply it, updated version of startup scripts (the ones packaged before unfortunately had some bugs), and latest build of the TSR.

Also for those who have interest in playing vanilla game with a C-Media PCI soundcard, or are using VSBCMI: looking at the code and listening to Heretic in headphone during last few days made me realize I am uncomfortable with fixup that VSBCMI performs for games code, and how this can potentially be messing up the games critical sections. I have published an updated version of VSBCMI which does not include the fixup and requires SETPVI to be run before any game that relies on POPF to restore interrupts state post CLI - e.g. Heretic will simply hand at startup otherwise. It is a bit of an experiment, but I think I may be hearing fewer clicks and scratching in Heretic post this change.