This is not Miku. Black Rock Shooter is something totally different than Vocaloid. I don't see why people put them together. BRS is a RPG game for the PSP and Vocaloid is a Computer Software. This is simply BRS is Miku Append's clothing. I just wanted to clear that up. Yes this picture is badass.
No, it was officially done. BRS is not just a game. The character started out as artwork by the creator and artist Huke. From there, spawned an anime OVA, then an actual anime series, then a videogame. Miku sang the theme song for the anime series.