The guys from ChampGames are currently working on an amazing home port of Galaga for the Atari 2600. I'm adding a video below so you can see the game in action but head to the thread in AA to get the demo binary: Champ Games - Galaga 2600 (http://atariage.com/forums/topic/291235-champ-games-galaga-2600/page-4#entry4288074).
https://youtu.be/RP50_I6z4KM