It does not; I just verified it, and this was already mentioned more than once. Since people can't seem to pay attention:

Half-Life: Source: RUNS WITHOUT STEAM
Half-Life 2: RUNS WITHOUT STEAM

Apparently Half-Life: Alyx is also DRM-free, according to a different DRM-free Steam game list, but I don't have it.

but thats a bit pointless? how do you run it if not through some kind of VR software, which in case would be easiest with SteamVR? You have some games that can for example run in native Oculus mode, but that only work if you have an Oculus headset, and Half-Life: Alyx can't run on it.

I have both an Valve Index and a Quest 2, but it never occured to me to try to start a VR game outside a VR framework...

I think all Steam does is implement OpenXR same as a web browser does. There are other implementations of OpenXR besides Valve's such as PimaxXR which performs way better than Valve's. MS has one, HTC has one, Varjo has one, Bytedance has one, Collabra has one, etc. There's nothing that special about SteamVR.

Aside from the various VR implementations, there's a mod where you can play it without VR.

I might be wrong, but as i understant it OpenXR is an open framework that still need specific runtimes to work on different headsets. by itself, it is not much more than a set of libraries. the different companies / developers then make use of these libraries and tailor it to their headsets. so for example the Meta runtime work on Oculus devices, VIVE OpenXR works for HTC VIVE headsets and so on. SteamVR do use OpenXR, but is a bit unique in that it seems to work for most headsets, and not only Valve Index specific (at least right out of the box). .

I am not sure what make PimaxXR "way better" than SteamVR at the moment. As the name says, it is specificly aimed towards the Pimax headsets (https://pimax.com/), Pimax is a good headset, it probably has the best screens of any of them, but it is also expensive as heck. At the moment, the compatability with PC VR games seems a little limited through PrimaxXR specificly.

but then again, I am not a programmer and do not know much about software, so I am probably wrong.

It's just much more efficient, so you get higher frame rates. If you lookup videos of people trying to run MS Flight Sim for example on a Pimax Crystal you will almost always find them using it instead of SteamVR for that reason.

Use Xash 3D Engine if you want to run HL1 without DRM.
-> https://www.moddb.com/engines/xash3d-engine

Xash ain't protected.

aye, but you need a Pimax headset for it, and then it is just as much about the hardware in the Pimax as it is with the software. I can not, for example, use PimaxXR for my Index or Quest 2, so for me it is a moot point.

However, I can use SteamVR for my Index and Quest 2, and if i had a Pimax it would work for that too. so perhaps why SteamVR is a bit slower compared to PimaxXR on a Pimax may also be due to universiality vs optimisation

Obviously. My point is that everybody can make their own implementation of OpenXR and you don't need SteamVR. You said you did not know how it was better and I told you. It's faster.

it is fatser for Pimax headsets. but if you do not have one... *shrug*.... you kind of ignored everything I said there, but that's fine.

Yeah apparently we can't talk to each other. Because you are missing the whole point too.

let me ask you this. if I want to play Half-Life: Alyx right now, and I do not want to use SteamVR, perhaps use a framework that is "better" or "faster". given that I have a Quest 2 and an Index - what choice do I have?

I don't have those devices. Bu if you use a Valve Index I would assume Steam is mandatory. For Oculus though I'm pretty sure their OpenXR implementation would be installed as part of the Oculus App.

I'm pretty sure you had the choice to buy a different product. But I don't know maybe you are locked in to Steam for your situation.