Heavenstrike Rivals was a free-to-play social tactical RPG for mobile devices. Players commanded armies of units to battle a sinister race of demons known as the Fallen. Several Square Enix franchise characters, including those from the worlds of Final Fantasy, appeared as playable units.

Long ago, a land hung amongst the clouds, suspended by monolithic chains: Lunnain. The land was watched over by the Guardian, a holy being who resided at the chains' summit. Every hundred years, the divine Seven Sisters awoke to choose a new Guardian. Under their care, Lunnain enjoyed 600 years of prosperity, growing into a bustling industrial metropolis. That was, until the Fallen came. Ruthless monsters of nightmare, they mounted daily attacks down the chains. Overwhelmed, the army of Lunnain retreated to focus its efforts on key locations. Thus, the city was irreconcilably split in two: the safe Havens, and the unguarded Forsaken. Punished by their deity and left behind by their government, these people struggle to survive each day; their lives—and their city—a shadow of past glory. But adversity has a habit of birthing heroism, and one who will shape this cursed land's destiny is about to arise...