in the second half of the 90s I owned a Sega Saturn. Since the Saturn was an abysmal failure in America I only own three good games for it. One of those three is Darius Gaiden.
Darius Gaiden Is a shoot'em up developed by Tokyo-based Taito better known for space invaders, Bubble Bobble and Bust A Move. Originally released in arcades in 1994 "gaijin" is notable as the first in the series that anyone cares about. It was later ported to the Saturn in 1996 as well as PlayStation and Windows in 1999. So if you're wondering why you've never heard of this game that's probably why.
Unlike Taito's own space invaders Darius Gaiden is a "side scrolling" shooter (like defender or 1943: The Battle of Midway). Though it does have one similarity to space invaders: your enemies are ill tempered sea life... FROM SPACE! Every enemy bigger than yourself is based on an obscure fish and the bosses have amusing names like "Great Thing" the sperm whale or a sea anemone named "Electric Fan". And it is a smaller angry fish can be "recruited" by shooting a crystal ball thing on her head. Then after catching it they will fight for you before combusting and exploding. Also halfway through the game The player jumps into hyperspace which looks like the psychedelic visions of the 70s meets the future of 80s. GROOVY!
Darius Gaiden has a similar level progression as Sega's "OutRun": at the end of each level you are asked to choose between a easier level and a harder level. I say "easier" as a relative term Darius Gaiden is a very hard game (no matter what you do to make it easier). You always lose something when you die; your main firepower gets downgraded every time you die and the strength of your force field thing will reset after using a continue. Your missiles, that costly fire diagonally, are the only power ups that persist through death. It's a game that never lets up those robot fish are dead and they want you dead NOW!
Ever since Square Enix bought Taito in 2005 their business has consisted of making new versions of space invaders and porting it and bust a move to everything with the screen. Neither party seems interested in releasing this game to PSN or XBLA even though that's the popular thing to do with classical games now.
One more thing, this game has a love of explosions unseen since Star Wars.
(Gaiden is a Japanese word that translates to "tale" or "side story" which is odd because this game doesn't really have one.)