Hello guix!
How I reported today on the IRC #guix channel:
We might have a problem on how retroarch is packaged. I've never used it, tried just now. There's the "core download" section where it downloads "$core.so.zip". Those are .so files: .config/retroarch/cores/atari800_libretro.so: file format elf64-x86-64.
I think we should either compile them and ship them or remove the download section or something.
Also, when downloading cores there are no license info
nckx provided this [1] as a useful link. It seems that some of the plugins are available for non-commercial projects only (so not compatible with the GPLv3, used by retroarch).
It is something we should investigate and address, both for licensing issues and for safety (and because we do not want to ship precompiled binaries).
Thanks, Nicolò