Works for me with Oculus Rift + Steam VR 1.8.21. Start Steam - Start Steam VR - Run the angry-birds-vr-isle-of-pigs.exe. Version 2.6.41.178 is "old" - this means I do not see the updated/included Level Editor :(
I managed to get it, by disabling the realtime security stuff of Windows 10, and redownloading the game, then I reactivated it. Hopefully my PC is not infected… 😲
how come is that ?