The first (and only) cartridge we look at in this article is Valkyrie No Bouken by Namcot.
Now, in case you didn't know, A lot of third party developers on the famicom made unique cartridge casing for their games. Why? No idea, but most of them do look cool, or at least are more interesting than the generic NES cart. Namcot, the name namco went by for some famicom games (multiple theories exist as to why this was done), created a uniform (to my knowledge) cart design for most of their games.