Nightmare Castle is an extended technical demonstration and a surreal adventure game, built as a platform to test reduction and refinement of RPG Maker's VFX to PC-88 or early PC-98 standards. As such, the game uses 3-bit graphics at a resolution of 640x400. A re-imagining of Amiha's Nightmare Castle, the game uses an 8-color palette and minimalist audio with Yume Nikki-style gameplay.