Gradius ReBirth is a side-scrolling 2D shooter much like previous Gradius games, and has been described as a "remix" of levels from past games rather than an entirely new game. The game features two modes: a standard game with unlimited credits and a Score Attack mode where players are only given a single credit to beat the game. Score Attack also supports online leaderboards. The game features five different types of ships to choose from, and five stages in total, with each (except the first stage) having its own original boss at the end.
This game takes place in the Gradian Year 6664, two years before "The Silent Nightmare Incident". The planet Antichthon, a protectorate of the Gradian Empire, suddenly and mysteriously falls silent. A report was made by the Director General of the Space Science Agency, Dr. Venom, which mentions that Antichthon's mother computer was now under the control of the Bacterians.
Realizing that a threat from the Bacterians may be imminent, the Gradian Government deploys its Gradian forces to combat the threat. Among them is Special Colonel James Burton, who had defeated the Bacterians a few years ago. Armed with an A.I. program called Gaudie, James Burton sets out in the hyperspace fighter known as the Vic Viper, in the hopes that he can combat the new Bacterian threat. But little does James know that there's much more in store for him...