Legacy of Kain: Dead Sun was a cancelled action-adventure video game developed by Climax Studios for Square Enix Europe, with an accompanying multiplayer component developed separately by Psyonix. Leaks described Dead Sun as a story-based action-adventure inspired by Legacy of Kain: Soul Reaver (1999) (the second installment in the series) and Nintendo's The Legend of Zelda. The game featured an open world and combined cinematic, violent combat with dungeon crawls, puzzles, and boss encounters. Links to past Legacy of Kain entries figured into the design, such as the shifting mechanic of the Soul Reaver titles, which enabled players to alternate between two planes of existence.

According to Divine Shadow's sources, Legacy of Kain: Dead Sun was not a reboot; it existed within established Legacy of Kain continuity. Its single-player storyline was to take place in Nosgoth's distant future, in an unfamiliar time period, even later than the events of Soul Reaver. This had been mandated by Square Enix, as had the instruction to develop a new main character. Legacy of Kain: Dead Sun was to introduce the devoutly-religious Saradin, a new sub-race of vampires, with blue skin, and the abilities to devour souls and shift between the Material and Spectral Realms. The Saradin vampire Gein, and the human Asher, were to act as the game's protagonists: their souls, bound together in an accidental phenomenon, would – much like Kain and Raziel before them – embark on a journey which, though initially motivated by revenge, would escalate to decide the fate of Nosgoth as a whole. The character of the Elder God was fundamentally involved. Story synopsis Divine Shadow delivered the following specific points of information regarding the planned story: • "A distant continuation of the series – in the same way that Doctor Who and Star Trek: The Next Generation took place in the same universe but were not immediate continuations of previous events. " • "Legacy of Kain: Dead Sun is set in Nosgoth's far future, long after the events of Soul Reaver. " • "There is a race of blue-skinned vampires living in this era –known as the Saradin. The vampires have evolved beyond those seen in the series previously, and have the ability to shift between spectral and material realms at will – and to consume souls. The vampires are devoutly religious. " • "Gein is one of these Saradin vampires, and he attacks a human of Nosgoth called Asher. Gein kills Asher and begins to feed on his soul. Something happens here that causes Asher's human soul to accidentally become bound in Gein's body. Gein becomes a unique creature, a human soul in control of (and trapped in) a vampire body. " • "Gein/Asher attempts to return to his human village, but during his absence the settlement has been attacked and torched. Gein/Asher unsuccessfully attempts suicide. " • "Gein/Asher explores Nosgoth with his new abilities. His quest for revenge against the destroyers of his village and those responsible for his circumstances – becomes a quest that will decide the fate of the world, as per Legacy of Kain tradition. " • "Asher (the human trapped in the vampire body) begins to realise that Gein (the original vampire soul of the body) is still present. Gein appears to Asher in visions, providing a vampiric perspective and alternate insight into the game's events. " • "The story would have explored the mystery surrounding a very old vampire child, and revolved around The Elder God. Religion was one of the game's overarching themes. " • "Further story links to previous games. "―Divine Shadow The meaning of the game's title, "Legacy of Kain: Dead Sun", was not revealed (if it had any).