LÖVR
Lua Virtual Reality engine
... optimized single-pass stereo rendering. Out of the box you get fast stereo rendering, VR controllers, hand tracking, haptics, spatial audio, 3D physics, PBR materials, SDF fonts, multiplayer, and more. The entire engine is 1MB and runs on LuaJIT, the fastest JIT compiler round these parts. Projects are just folders with scripts and assets in them, organized however you want.