United Kingdom Britcoin (UKB) has been around for years:
http://galaxies.mygamesonline.org/digitalisassets.htmlThe big problem is securing the blockchain. Look at the value per coin. No way that would be secure with the garbage wet-paper-bag levels of hashing the vast majority of altcoins have.
Thus UKB, like the other "nation" and "corp" coins that came out around that same time (years ago now), were forced to temporarily move to using an Open Transactions format until such time as their transaction volumes are large enough that transaction fees will be able to afford enough mining to actually secure such valuable blockchains.
-MarkM-