What are the stack and knowledge required to create a very basic vr game?

Depends on what your goal with this is. If you're trying to learn VR dev and haven't done any game dev before, you don't need to (and shouldn't, especially not at first) create everything from scratch. Use something like Unity, with its Asset Store and plugins like SteamVR so you can get started and focus on scripting a core gameplay loop and creating a simple game and level.

Then, pick up Blender or Maya to create/rig/animate assets or levels if you are interested in that side of things. Physics is usually handled at the engine level but you might want to delve deeper and tweak for your liking as you gain more hands-on experience.