Headache: Altered States is a psychedelic adventure game created with RPG Maker MV. In it, the player explores psychedelic worlds shaped under the influence of the substance "Nix."

The plot follows a protagonist who takes the fictional hallucinogenic substance "Nix" to use its effects for writing a truly unique book. By the end of the game, she realizes that due to the substance and her inner struggles, she is slowly destroying herself, and decides to quit the drug and change her life.

The gameplay of Headache revolves around exploring surreal worlds filled with enemies, secrets, and side activities. The player’s goal is to find ideas for writing the book. These ideas are hidden behind tall wooden doors marked with a book-shaped lock. Each session requires the player to find one idea, after which gameplay returns to the real world.

The game takes place over the course of 7 days , alternating between gameplay in the real world and gameplay during the trip sequences.