One night, little Giana from Milano has been sleeping deeply and has a strange dream. She is suddenly in a mysterious world where everything is different.
Gravity is not as usual and she sometimes feels as if she can fly. There are some odd figures and structures all over. Abandoned castles and old grottos seem to keep many secret treasures. To get out of this world she has to find the magic, huge diamond (Great DeGaulle Stone). At the end Giana is not alone in this adventure, her little sister Maria is dreaming as well, in which she travels through 32 stages full of monsters, while collecting ominous Diamonds. If the player wins the final battle, Giana will be awakened.
The Great Giana Sisters is a 2D side-scrolling arcade game in which the player controls either Giana or her sister Maria. The game supports alternating 2 players, with second player taking control of Maria.
Each level contains a number of Diamonds, (which the manual calls Dream Crystals) which gives points when collected in order to make the game's high score. An extra life can be gained by collecting 100 Dream Crystals. Extra lives can also be found in the form of hidden "Lollipop" items.
Enemies can be defeated by jumping on them or shooting them after obtaining the relevant powerups. The enemies include Owls, rolling eyeballs, flesh-eating fish and deadly insects. The "Fire Wheel" transforms Giana into a punk with the ability to crush rocks by jumping beneath them. "Lightning" awards Giana "Dream Bubbles", a single projectile shot. "Double Lightning" gives her ability to shoot recoiling projectiles. "Strawberry" gives the ability to shoot homing projectiles. There is one defensive item in the game, the "Water Drop", which protects Giana against fire. A number of special items can also be triggered that affects the entire screen, such as the "Clock", which freezes all enemies on-screen, and the "Magic Bomb" kills all enemies. These items are found in the item blocks scattered around the stages.
There are two types of stages in the game, an "Overworld" and "Underground" stage. The "Overworld stages" feature green scenery and pipe-shaped objects, along with bottomless pits for Giana to avoid. The "Underground" stages feature additional hazards such as water and fire, as well as bosses.
There are in total 32 stages in the game. Hidden "Warp-Blocks" can be found to jump through portions of the game.
The Great Giana Sisters was programmed by Armin Gessert, with graphics by Manfred Trenz and a soundtrack composed by Chris Hülsbeck under the label of Time Warp Production Inc, under the publisher Rainbow Arts. The first original game version was released in 1987 on Commodore 64. Shortly after, it was released on Amiga, Amstrad CPC, Atari ST. From 1994 until going into administration in 2012, the license was held by Spellbound Entertainment, founded by the former Giana programmer Armi Gessert, which later on released Giana Sisters DS on April 3rd 2009 in the EU, but Armin died of a heart attack in November 8th, barely seven months after the game's release. The license is currently held by Black Forest Games, who have developed the modern sequel Giana Sisters: Twisted Dreams. On August 25, 2017, Swedish publisher THQ Nordic acquired Black Forest Games and all it's assets, with all but five founders and fifty members remaining on board. Since acquisition, THQ Nordic has made no announcement regarding the future of the series but has Black Forest Games presently working on Fade To Silence, which is available for Early Access on Steam (to mixed reviews).
The game has been ported to numerous systems since its release. A planned port for the ZX Spectrum was reviewed in magazines, though eventually cancelled due to legal pressures. In 1993, Dutch developer Sunrise released a version for the MSX, programmed by Jan van Valburg. Unofficially, the game has been cloned on Windows, DOS, Linux, Mac OS X, AmigaOS 4, NetBSD, AROS, MorphOS, and Symbian OS. An unofficial port of the Commodore 64 version was also made for the Nintendo DS.
In 2006, a mobile version of the game, titled simply Giana Sisters, was released for J2ME feature phones. It also had art done by Mathias "Tikwa" Neumann who later went on to make the Giana Sisters: Twisted Dreams comic book.