Ningyo no Rakuin is a tactical horror RPG inspired by the works of Howard Phillips Lovecraft. Between the fanatical quasi-human tribesmen, the Deep Ones rising from beneath the waves, and the grad student from Miskatonic University, there are more references to the Mythos than you can shake a shoggoth at. The plot itself is fast-paced, centering first on surviving the dangers of the island and later on rescuing the main character's girlfriend from a particularly nasty fate involving an unnamed Elder God and a transformation into a fishy abomination. Elements of the storyline play out before and after (and sometimes during) each battle, and the interludes between battle chapters include a short summary of recent events leading up to the current plot point.