"The Apothecary of Trubiz" is a short puzzle game where players step into the role of an apothecary (Kusushi). The core challenge involves deciphering a manual written in a fictional language to learn how to mix potions and prescribe them to patients.

Players must first deduce two key pieces of information from the manual's unfamiliar characters: what ingredients combine to create a specific potion and what symptoms that potion treats. The game's progression centers on gradually deciphering the language, uncovering the rules for mixing and prescribing, and ultimately guiding patients toward the correct treatment. Prescribing potions can have varied results: patients might recover, or their symptoms could worsen. The story features a slight branching ending that depends on the success or failure of the player's actions.