On amd64, games-q3mod eclass depends on app-emulation/emul-linux-x86-baselibs. This is not needed, however, because 1. There is a 64-bit Quake III Arena version (ioquake3, games-fps/quake3 in Portage), and the eclass has an option to use it; 2. Quake III Arena mods anyway are normally compiled for the Quake 3 Virtual Machine, which is not related to any real architecture - Quake III Arena compiles QVM code to target arch at run time, or uses an interpreter if there is no corresponding compiler. Reproducible: Always Steps to Reproduce:
The only thing left using games-q3mod now is quake3-urbanterror and that'll be removed soon.