well am sugesting to add one more colony we can build instead 21 to make 22 instead
what you think about that?

http://i1097.photobucket.com/albums/g343/Akatcuki/Peinxd2323555.jpg

there should be no limit on the colonies can build

Oh yes there should be, or else all of the universes would quickly run out of space.

How would you react if a player decided to annoy everybody by building a thousand colony ships and colonized a planet with each and every one?

I think 21, or as Pein suggests, 22, is enough.

When you think about it, you get one home planet and 20 colonies. I think that any more than that would be too much.