One of the rarest games for the PC Engine, Darius Alpha was only offered to those who bought both the CD and HuCard versions of Darius Plus (Which doesn't make much sense, considering how similar the two versions are). People who just couldn't get enough of Darius could now play another variation on the same theme. Darius Alpha is built on the same codebase as Darius Plus, but has been remodeled into a so-called "boss-fight" game, e.g. a game where you only fight the bosses of a game or game series. You start out with an unequipped ship and must take down the boss of the first level, King Fossil. Upon defeating King Fossil, you are granted some slight upgrades and proceed directly to the boss of the next level. And so on.