What a core is
RetroXR is not itself an emulator. It is a room that runs libretro cores — and a core is an emulator for one system, packaged so a program like this one can load it.
That is why the app arrives with none of them. You download the cores for the systems you actually care about, from inside the headset, and RetroXR runs them.
What this gets you
Section titled “What this gets you”Anything libretro supports, RetroXR can play: NES, SNES, Mega Drive, Nintendo 64, PlayStation, Saturn, Dreamcast, GameCube, Game Boy through to the DS and 3DS, PSP, plus the long tail — Neo Geo Pocket, WonderSwan, Virtual Boy, Amiga, C64, MSX, DOS, ScummVM, arcade boards, and fantasy consoles like PICO-8.
RetroXR knows about 76 systems. How many of them you can play comes down to which cores you install and which BIOS files you own.
Several cores per system
Section titled “Several cores per system”Most systems have more than one core, and they are not interchangeable. One may be more accurate; another faster; another may support something specific.
Where one core is clearly the right default, it is marked recommended — take that one unless you have a reason not to. The Nintendo 3DS is the example worth knowing: its recommended core renders in stereoscopic 3D, which in a headset is the entire point, and the alternatives do not.
Where cores come from
Section titled “Where cores come from”Cores are downloaded from the libretro build server, the same source every libretro frontend uses. Nothing is bundled with RetroXR and nothing is scraped from anywhere unusual.