Crystalis, originally released in Japan as God Slayer: Haruka Tenkū no Sonata (ゴッド・スレイヤー はるか天空のソナタ, lit. "God Slayer: Sonata of the Far Away Sky"), is a 1990 action RPG/action-adventure video game produced by SNK for the Nintendo Entertainment System.
Though Crystalis never became a runaway hit, it is now considered a cult classic. The game's initial success prompted a release for the Game Boy Color by Nintendo Software Technology in 2000, which is generally considered more of a remake than a simple port. Many changes were made to the story, music, and other aspects of the game, upsetting fans of the original.
The game begins with a man's awakening from a cryogenic sleep one hundred years after a global nuclear war. Even though he is unable to recall his name or who he was, he begins to discover that he may be the key to save this world from destruction. Aided by four wise sages and a mysterious woman, he rises up against the tyrannical Draygonia Empire to ensure that humanity ultimately has a future.