Galaga: Tekken 20th Anniversary Edition combines the shoot 'em up gameplay of Galaga with characters from fighting game franchise Tekken. The player can choose from four characters, one for each of the three lives and these are then controlled just like the spaceship in the original Galaga, moving left and right and shooting at the enemies that appear above.
The characters differ in abilities with different bullet types and firing speed. The enemies, which also are based on characters from the Tekken games take their places in a formation at the top of the screen and then begin flying down towards the player who has to avoid getting hit. Like in the original Galaga the player can get captured by the enemy. The difference here is that when rescuing the captured ship, other famous Namco characters such as Pac-Man will enter the game. As he moves across the screen any enemy that remains in his path will get killed. Other characters that make appearances are Mappy and Dig Dug.