DoctorGOGgles: Race the Sun is version 1.531 on Steam and 1.51 on GOG.
Version 1.531 adds support for VR, which is missing from the version on GOG.
Note that VR games which use SteamVR don't actually need Steam to work. SteamVR is only a framework for VR support. You can install it via Steam, but you don't need to have Steam installed to run VR games which support it.
MIND: Path to Thalamus supports VR via SteamVR in the version available on GOG, so an up-to-date version of Race the Sun with VR support should also be possible on GOG.
tremere110: SteamVR isn't permitted to be distributed without Steam. It would be in a very murky legal area for GoG or the Race the Sun developers to provide it without direct authorization from Steam. Go ask Steam support about distributing it and see what they say.
I beg to differ! There are already Games with SteamVR support on GOG and that's no legal problem, as long as they don't ship an installer for the SteamVR framework with the game!
The GOG version of MIND: Path to Thalamus doesn't ship with an installer for SteamVR, but it does support SteamVR if you have it already installed on your system. It automatically detects and starts SteamVR, so you can play the game in VR mode.
There are many games you can buy outside of Steam that support VR via SteamVR. You just have to install SteamVR yourself first for VR to actually work. It's the same situation with Race the Sun. There's no legal problem for the devs if they update the game on GOG to support SteamVR, they just can't ship an installer for SteamVR together with the game.
You can make games with
Unreal Engine or
Unity that support VR via SteamVR and legally distribute them yourself, give them away, sell them on GOG, itchi.io, Steam, wherever. You just can't ship an installer for the SteamVR framework itself.
By the way, Race the Sun dosn't automatically install SteamVR when you install the game on Steam. Even on Steam you have to install SteamVR yourself if you want VR support in Race the Sun.