Gantz: O (2016) is a visually spectacular CGI anime film that plunges viewers into a brutal and high-stakes sci-fi universe. Based on the popular manga series, the story follows high school student Masaru Kato, who is tragically murdered in a subway station only to awaken in a mysterious apartment. There, he finds himself resurrected and conscripted by a strange, black sphere known as Gantz. Alongside other recently deceased individuals, Kato is forced to participate in a deadly game, battling a horde of terrifying and bizarre alien creatures that have invaded Osaka.

The film's greatest strength is its breathtaking animation. Rendered in cutting-edge 3D CGI, the action sequences are fluid, visceral, and incredibly detailed, bringing the grotesque alien designs and chaotic urban combat to life with a cinematic weight rarely seen in anime adaptations. The direction maintains a relentless pace, balancing moments of character development with explosive set pieces. While the plot focuses primarily on the mission in Osaka, it effectively introduces the core concepts of the Gantz world—the mystery, the violence, and the psychological toll on its participants.

Viewers should watch Gantz: O for its unparalleled visual spectacle and raw, unfiltered action. It serves as a perfect entry point for newcomers to the franchise and a thrilling treat for existing fans. The film condenses the manga's intense atmosphere into a cohesive 95-minute experience, delivering on its premise with stunning technical prowess and a compelling, if straightforward, narrative of survival against impossible odds.