If you're looking for anime similar to R20: Ginga Kuukou, you might like these titles.
Portrays the lives of two men, Jack and Al, as they confront various hardships in the vast world of outer space. All action and scenery in the unexplored parts of the Moon will be illustrated using an innovative type of animation unlike any seen before. My sincere wish is that this project inspires contemporary lives everywhere.
In AD 2387, mankind has colonized the galaxy, including Planet Maris - "Second Earth.". Unfortunately for humanity, the Noza space invaders have plans of their own and launch an attack. However, a shred of hope remains: from the corners of the galaxy, three guns known as Zillion were acquired; with them, mankind just might have a chance against the Noza. Against all odds, Champ, Apple and J.J. - members of an elite task force - must wield the Zillion and put a stop to the invaders!
Team Pied Piper is assigned to take part in a special festival in Switzerland as part of Generation Bleu's public relations policy, but Fleur and Elena have Ao dress up as a girl much to his chagrin. At the festival, the trio find themselves running away from an insistent journalist until they are called back to confront a Secret that appears on the border of Italy.
Agate is a mysterious boy on his way to the prestigious Cluster Edge E.A. School. He discovers a new power that he never knew he possessed, and its power to change the world.