Make the Galagas stop firing.
Just like in the arcade version of Galaga, you can make the enemies stop firing missiles. In round 1, kill everything but the two left flies on the bottom row. Let them fly around for about 15-20 minutes, until they stop firing their missiles. Kill them, and for the rest of the game, none of the enemies will shoot at you.
Contributed By: RaydenLord.
Dig Dug Cheats
Make every enemy dissapear!
This glitch will make all enemies dissapear in the current level, but the level will not end. This let's you to get as many points as you want from eating all the dirt! 1) Get the game down to two Pookas. If you only leave one, it will escape thus ending the round. 2) This works best in horizontal tunnels under the rocks. 3) Get a Pooka to follow you, inflate as necessary to delay him a little. 4) Right when you are next to the rock, inflate the Pooka once to just delay him. When he moves at your character again, move under the rock. 5) Quickly turn around and start pumping the Pooka up. Using the delay of the rock dropping, you should be able to cause the Pooka to burst at the same time the rock drops on him. 6) If you are successful, then the other Pooka will disappear and you can amuse yourself digging out tunnels all day long in the dirt. NOTE: To return the game back to normal, drop another rock and you will go into the next round.
Contributed By: Apalapan.
Stop Enemies from Firing
On most revisions of Galaga, there's a trick that stops enemies from firing at your ship. In Stage 1, kill all aliens except the two bees in the bottom-left corner. Allow the bees to dive down and shoot at you, while dodging their shots. After around 15 minutes or so, the bees will continue to drop down, but they won't fire. Let them drop down another 5 or 6 times, then kill them. After all this, enemies will not shoot at you for the rest of the game.
Contributed By: Colin.
Wait until one of the top ships(the green ones that take two shots to kill) comes down and fires off a tractor beam(the beam that can capture your ship). Let it capture your ship. Now, wait until it swoops down again with your ship behind it. Simply kill the head ship(the green one), and it will lose your ship. Your ship will then lock on to the side of your current ship, giving you two ships to play with at the same time! Now, be careful. Not only will both ships be firing at you after your ship gets captured, but if you accidently shoot your captured ship, you'll destroy it. Also note, this will cost you one life, but will definately make the Challenging Stages, and perhaps the game itself, a little easier to play.
Note: This works in all non-bootleg/hack versions of Galaga, as well as most of the sequels and Arranged Mode in Namco Classic Collection Vol. 1.
Contributed By: Joseph Collins.