All known civilizations are humanoid. Most of them are indistinguishable from earthlings, while others differ slightly (for example, they might have grey skin or can bear extremely cold or hot temperatures) but still very similar. The reason for the appearance of so many humanoid civilizations is known - a long time ago, mysterious beings only known as the Seeders "seeded" the Earth-like planets of the galaxy with life. After that, they disappeared without a trace. The study of what remains of their culture shows that their level of development was much higher than the current galactic standard. Specifically, they were able to travel through time. It is believed that the Seeders were at war with someone, but no one knows who were their enemies.