Gurei is an indie action-adventure game where you play as Rei, a human spirit who must defeat powerful natural entities called "kami" to absorb their abilities. The game's signature feature is a dynamic difficulty system that allows you to fight bosses in any order, with each kami's power depending on your chosen path meaning your first fight could be someone else's final boss. Each defeated kami grants Rei a unique skill, such as a boosted dash, finishing attacks, or healing, expanding your combat capabilities beyond basic sword strikes, dodges, and kicks. The nonlinear structure encourages experimentation, allowing you to backtrack and try different approaches when you get stuck.