CYST - a body horror RPG

A visceral roleplaying game of flesh, fear, and becoming.

There is something growing beneath the skin.

You are the Growth: an intelligent cyst, tumour, pustule, or parasite with a will of your own. You live inside a human Host who never asked for you. They want to be free. They will cut, burn, starve, or sedate you. You offer something else: power.

Each turn is a battle of wills. The Host struggles to survive and remain in control. The Growth spreads, mutates, and infiltrates new organs. With every inch of tissue conquered, you unlock new abilities: chemical suggestion, spore clouds, neural override. Your goal is simple: reach the brain and overwrite the Host’s identity. Become them.

But every step risks exposure. Every new power comes with grotesque side effects. The more the Host resists, the closer they edge toward panic, or violence, or death.

CYST is a standalone horror RPG. You play the Growth. One can play the Host, using a behaviour table and anxiety track to guide their actions. Designed for short, intense sessions filled with uncomfortable choices, escalating dread, and horrific intimacy.