Sorry for necropost, but THX alot for this tip! I tweaked around quite a bit and tried to cross my eye as hard as I can, but viewpoints felt like 2 meters apart before enabling parallel projections. (This is what "Compatible with parallel projections" in fckn PiTool actually does, it just enables it. Button should say: Game NOT compatible without parallel projection, enable it..)

(In new PiTool the option to add custom EXE files seems to be gone, so I used the "Common Settings" to enable parallel projection for now.)

Do you maybe have any other tips to get it running smooth? I get like 20-40 FPS without oversampling, while my RTX 2070 Super is totally bored at around 20%.

FYI, I manually installed the newest version from github:
https://github.com/Pescorr/Gmod-VRMod-Semioffcial