games-emulation/gems is currently only keyworded for x86, although it can be built successfully on amd64 with ABI="x86". So, with this patch, I believe it can be keyworded ~amd64 as well as x86. Unfortunately, it still builds a 32-bit executable, so it will have to be package.mask'd in the no-multilib profiles. Reproducible: Always
Created attachment 262081 [details, diff] Ebuild patch to allow games-emulation/gens to build on amd64 multilib
Sorry it does not work here.