''The core concept is definitely Galaga-like. It's as if someone sat down and decided to make an entire game out of the "challenging stage" bonus rounds found in the original Galaga. But rather than shooting for accuracy and trying to hit everything, as you did in the '80s, Legions doesn't seem to care if you hit everything or not. It's more about surviving the looping and swooping ships that are constantly flying into and out of the screen.
You'll fight off the enemy by shooting them, naturally. Your ship can only fire up, as normal, but you can move around the screen at will. You also have two satellite cannons that can be deployed at any time using the right stick. Unlike your main ship, the satellites can fire up, down, left, or right depending on which direction you push. You can pick up your satellites by touching them, or a tap of the left bumper will send them back to you. Immediately before ships fly onto the screen, a set of streaky lines details the path of the incoming ships, giving you a moment to set up your satellites and prepare for the attack. The enemies rarely shoot at you, so you're mainly trying to avoid collisions while racking up as high of a score as you can. Eliminating enemies in quick succession, or hitting an explosive ship that takes out all the other enemies in that wave, brings your score multiplier up. It drains very quickly, though, so it doesn't seem like it's one of those action puzzle games where you can do some kind of full combo the whole way through.
Galaga's other defining feature was the way the boss ships would come down and spit out a tractor beam, capturing one of your ships. You could then free your captured ship and dock it with your new one, giving you double firepower. But Galaga Legions instead bases its capturing mechanic off of Gaplus (Galaga's direct sequel), where you could capture enemy ships and use them for additional firepower. In Legions, this is accomplished using a big black hole-like ball that appears at a set point in every level. When you shoot it enough times, it activates, sucks up all the ships on screen, and gives them to you to control. The enemy ships deploy with your satellites, making them much more powerful.''