Regret Island is a non-linear horror role-playing game (RPG) incorporating elements of hentai, dating simulation, and visual novels. The narrative presents multiple branching paths and diverse problem-solving mechanisms. Character fatalities are permanent, and characters risk succumbing to madness. Gameplay necessitates the management of both personal and interpersonal "Lust & Insanity" levels. Synopsis: A familial unit and their companions undertake an international voyage, opting for a brief stopover on what appears to be a secluded island. As latent psychological tensions manifest, the seemingly idyllic excursion devolves into a sinister ordeal. Can players skillfully navigate the complexities of human behavior and achieve a successful escape from the island's clutches?