約定之日 is an immersive card game set in a post-apocalyptic world where humanity fights against monstrous creatures known as 災獸. Players take on the role of a '監察官', leading a team of magical beings called 魔女 to fend off these threats. The game features a rich narrative backdrop, where players must strategize and collaborate with their magical allies to protect humanity's last strongholds. Each encounter requires careful planning and resource management to overcome the formidable foes that threaten the peace achieved in the past.

The gameplay combines traditional card mechanics with unique character abilities, encouraging players to develop diverse strategies tailored to various challenges. With its captivating storyline and intricate gameplay, 約定之日 offers a compelling experience for fans of card games. The art style and thematic elements immerse players in a world filled with tension and hope, appealing to both casual gamers and those seeking deeper strategic elements.