After World War III, humans have finally achieved world peace - or so they thought. Malevolent aliens have infected the human organism in a most treacherous way possible, turning young and pretty women into rampaging, violent nymphomaniacs. Only one person can stop the insanity - the attractive secret agent with the codename Lyewärd. Guerrière Lyewärd is a side-scrolling beat-em-up. The gameplay is very simple: the player moves the protagonist through strictly linear stages from left to right, each containing a few types of female enemies that attack the heroine from both sides. The secret agent can punch, kick, and jump. Power-ups such as health-restoring hearts and invincibility appear at set points during the stages, floating in the air. Each stage culminates with a boss battle against a powerful female enemy; defeating the boss leads to a lesbian sex scene.