Gaplus is a fixed shooter arcade game that was released by Namco in 1984. It was the only other game to run on Namco Phozon hardware, and in the US, a modification kit was later released to change the name to Galaga 3, possibly to increase recognition among fans of the games even though there was no "Galaga 2".

Since Gaplus is a sequel to Galaga, it has similar gameplay. The player controls a spaceship, that can now move vertically (limited to halfway up the screen, much like Atari's Centipede) as well as horizontally, and shoots at swarms of incoming insect-like aliens which fly in formation above it and swoop down to attack it in akamikaze-like dive. In this sequel, the level starts over if the player gets killed before all the enemies have come in. When all enemies are killed, the player moves on to the next level. By obtaining certain powerups, it is possible to shoot sixty bullets per screen, the most any Galaxian-related game has.