Castle "hogs"
One annoying aspect of the game is that there are players who will occupy literally hundreds of castles at the same time. I find my castle surround by a sea of castles all occupied by the same player. Most of these are worthless 2's and 5's. There should be a limit. You've set limits on other aspects of the game such as weekly limit on raiding - there should be one of how many castles one can occupy at one time.
At least, in a sane world there would be!
Thank you.