Galaxies mode

Galaxies is the game's main mode, which presents the player with a series of ten solar systems, each with a number of different planets featuring different challenges or styles of play. All of the enemies from Retro Evolved appear in Galaxies, along with some new enemies with a variety of different behaviours.

Some planets play very similarly to Geometry Wars: Retro Evolved, while others introduce moving obstacles, narrow tunnels, enemy carriers that split into smaller enemies when destroyed, and other gameplay mechanics. Most levels start the player with three lives and three bombs, but some require the player to play with only one life and/or no bombs, and the player may not be able to earn extra lives or bombs in those levels. Each planet sets a Bronze, Silver and Gold score level, challenging the player to reach those scores before running out of lives. Bonus Geoms are awarded for earning each medal for the first time.

Most enemies in Galaxies mode will drop one or more yellow items when destroyed. Each of these items represents a quantity of Geoms, which are dropped in amounts of 10, 25, 50, and 100. Geoms serve a variety of purposes to the player: In the game, collecting a Geom container increases the score multiplier by one, up to a maximum of 150. The player is also awarded extra lives and bombs (except in certain levels) for collecting set quantities of Geoms. Once a game ends, the collected Geoms are added to the player's total, and can then be used to unlock drone behaviors and to unlock new galaxies and the planets within them.

An automated drone follows the player around each level, executing one of eight behaviors that the player can select from before starting the level. These behaviors include "Attack", which causes the drone to fire in the same direction as the player, "Defend", in which the drone fires opposite the player, "Collect", in which the drone zips around to collect Geoms as they are dropped, and "Bait", where the drone lures enemies away from the player. Each behavior aside from the default "Attack" must be unlocked by spending Geoms, and each behavior also "levels up" over time as the player uses it, increasing the drone's speed, power and/or accuracy.

The game keeps a table of high scores for each planet, as well as a cumulative high score per galaxy and across the game as a whole. Players can also upload their scores to a global online leaderboard via the Nintendo Wi-Fi Connection service.

Other modes

Galaxies offers several modes of multiplayer play. In Cooperative mode, two players each control their own ship but share the same score, multiplier, bombs and lives. Simultaneous mode plays similarly, except that each player has their own score and lives, and the players compete to achieve the higher score. The DS version includes an extra Versus mode, in which one player controls the ship and the other player spawns enemies to try to destroy it. In all multiplayer modes the support drone is not available, and if the players move toward opposite ends of the screen, the camera zooms out to keep them both in the frame.

The Nintendo DS and Wii editions of Galaxies can connect to one another wirelessly, allowing players to unlock an additional Galaxy to play in both versions. Both editions of the game can also transfer a version of Galaxies to a Nintendo DS via its Download Play feature. Retro Evolved is included in both editions of the game, allowing the player to play the game as it was released on Xbox Live Arcade (minus Achievements and Retro mode). Retro Evolved also supports an online leaderboard feature.