SiN Episodes were a planned series of episodic games for Microsoft Windows that would have expanded upon the 1998 computer game "SiN". A total of nine episodes were planned with only the first one released. Developed by Ritual Entertainment and powered by the Source game engine, the first episode "Emergence" was the first computer game by a major developer to both be produced episodically and delivered over the Internet without the intervention of a publisher. This was accomplished through Valve's Steam content delivery system.