dev-games/cardpics-0.4 works with the ~amd64-keyword; I had to change the SRC_URI, though: SRC_URI="http://savannah.gnu.org/download/cardpics/${P}.tar.bz2" (i.e. delete the "source/"-part at the end
Keyworded, and marked it stable because it's only a set of pictures.. nothing to test plus fixed SRC_URI