gentoo-overlay/games-arcade/commandergenius/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
	<herd>games</herd>
	<use>
		<flag name='tremor'>
			Use <pkg>media-libs/tremor</pkg> as ogg decoder
			instead of <pkg>media-libs/libvorbis</pkg>
		</flag>
	</use>
</pkgmetadata>