blackjack seems to be missing from the gentoo version of gnome-games while it is on the gnome ftp for every version can't find any trace of it in change log to say why not there
what version of gnome-games do you have installed? are you using any overlays? I have blackjack here.
you probably need USE=guile set for it.
no overlay and no use flag blackjack is now there im on on ~amd64 when i made the bug i wsa on stable maybe this could be diffrence but i also have it how
i had gnome 2.14.0 and the only overlay i have is for vmware-server and idesk-extras
user reported he now has blackjack.