All versions of the games-action/prismlauncher ebuild up until now (including the latest, 9.4) have included this line in pkg_postinst: > optfeature "built-in MangoHud support" games-util/mangohud This seems to have been carried over from the old games-action/polymc ebuild. However, the games-util/mangohud package isn't available in ::gentoo; instead, it's in the ::guru overlay. It seems to me that the reference to this package should probably be clarified to state that it's available in that overlay, in the same way that the games-util/lutris ebuild does - it's not necessarily obvious otherwise.