Zero-Sum Heart is a captivating adventure game set in a magical boarding school, where players follow the protagonist on her eighteenth birthday as she confronts a pivotal choice that alters her life. This two-hour story weaves together elements of romance, teen drama, and horror, culminating in multiple endings that reflect the character's decisions. The game features vibrant, psychedelic hand-drawn illustrations that enhance the surreal experience, alongside a witchy and atmospheric original soundtrack that complements the narrative's eerie tone.

Players will navigate a world filled with complex themes, including love without reciprocation, the consequences of power, and the struggle for identity. While the game does explore dark topics such as self-mutilation and toxic relationships, these are presented in a stylized manner, making them less graphic yet impactful. Caution is advised for those sensitive to these themes, as the story's premise involves elements of dubious consent in romantic interactions influenced by magic.