Another good wholesome anime about space and genocide is Uchuu Senkan Yamato, or Space Battleship Yamato, or Star Blazers in the English dub (first two seasons are great in a cheesy way but the third is awful).
Basically it's Earth being attacked by humanoid aliens, so Earth digs up an old sea ship and makes it into a space ship with this huge cannon called the wave motion cannon, then they go through space and fuck up everything that moves.
It's got a cool intro song too.
https://www.youtube.com/watch?v=LKe0wARmks4 