Much like previous installments in the "Darius" series, "G-Darius" is a horizontally scrolling shoot'em up. While the game features three-dimensional polygonal graphics, the gameplay remains two-dimensional. The player controls a spaceship named the Silver Hawk and must battle enemies and avoid obstacles throughout the game's stages (referred to as "zones" in the game). The ship is armed with forward-firing missiles, small aerial bombs and a protective force field. These can be upgraded by power-ups, in the form of large orbs, that are dropped by specially-colored enemies when they are destroyed. When the player reaches the end of a zone, a boss appears, which must be defeated to proceed. Once the boss of a zone is destroyed, the player is given a choice of which zone to play next via a branching path. There are 15 zones in total, numbered using the Greek letters alpha to omicron, however the player only needs to complete five in a row to reach one of five alternative endings. Each level also has two alternative routes that the player can choose about half way through. Some of these are duplicated in later stages but result in the bosses appearence and attack sequences being slightly different.