Hi 
At least for fixing Windows to 1809, you don’t need any special tool. Since I’ve got my problems, I found that you can configure Windows Update in the Group Policy to stick to whatever Windows version you want. As soon as set, Windows Update even doesn’t install any major improvement updates for the current version, as well, just security updates for Defender or small specific app-related updates.
Configure Windows Update for Business via Group Policy (Windows 10) - Windows Deployment | Microsoft Docs
I want to stay on a specific version
If you need a device to stay on a version beyond the point when deferrals on the next version would elapse or if you need to skip a version (for example, update fall release to fall release) use the Select the target Feature Update version setting instead of using the Specify when Preview Builds and Feature Updates are received setting for feature update deferrals. When you use this policy, specify the version that you want your device(s) to use. If you don’t update this before the device reaches end of service, the device will automatically be updated once it is 60 days past end of service for its edition.
When you set the target version policy, if you specify a feature update version that is older than your current version or set a value that isn’t valid, the device will not receive any feature updates until the policy is updated. When you specify target version policy, feature update deferrals will not be in effect.
=> At least, you can maintain that old version until its end of service.
Unfortunately, I don’t know whether 1809 already had EoS.
=> 1. So create a 1809-installation with the Media Creation Tool.
2. Do the major security, service and bug-fix updates for 1809.
3. Turn-off auto upgrade in the Local Group Policy as described above.
@Tridef-3D:
I have it, too, but only rarely use it since I’ve got the 5K+/8K-X and vorpX.
Main issue I have with almost any game turned into VR with vorpX, is, that the image’s depth doesn’t really fit completely - everything looks a bit as if it was too close. Even buildings, towers or towns at the horizon look as if it was not dozens of kilometers or more, but much much closer. That’s a bit weird, think, I have to play around with the 3D-depth setting.
When trying / playing with Tridef on my monitor, depth is okay.
So I think, games really have to be designed for VR, too, in order to look right.
Nevertheless, I am thankful that there is that possibility for VR with vorpX.
Any further recommendation is appreciated 