Trying to identify cartoon about two friends

Hello, a cartoon (animated series?) About two friends. As far as I remember, there was an ordinary world and two other realities (it seems like they were imaginary). In one of them there was a castle and one friend, if he left it, he became a rat, which was an allusion to fear. As far as I remember, at one moment he was able to overcome this. In the second reality, there was another planet with colonies of other creatures (similar to people) with whom these friends were friends, and also on this planet there was a different race that was against these creatures. As far as I remember, the cartoon was in 3D, but I can't be sure. Can’t even suggest a range, but, probably, it was created in late 2000s or early 2010s