How to solve castling effect?

[Taqwus]

Feh. Building lots of castles is rather expensive in gold, gems or blood slaves depending on how you do it -- unless you're astoundingly lucky with fortress sites and fortress events. If somebody's building castles everywhere, that's a lot of gold expended plus time consumed with commander-turns. Then garrisoning all those bloody castles is expensive unless they're undead, most of which defend the gates rather poorly.
You might as well argue that the game encourages having decent armies backed by mages.

[Norfleet]

Originally posted by Taqwus:
Then garrisoning all those bloody castles is expensive unless they're undead, most of which defend the gates rather poorly.

The castles AREN'T garrisoned: Usually, they're instead defended by mobile forces that teleport, gateway, or fly between the threatened castles. The drawback is that in order to make this in any way affordable, the castles tend to be constructed of paper and breach quickly, necessitating a rapid response: Attacking more castles than your opponent can respond to at once will pose major problems for him.

[NTJedi]

There should be some territories which prevents castles from being built. A territory with lots of rivers and sand for example.

[NTJedi]

Originally posted by Norfleet:
Attacking more castles than your opponent can respond to at once will pose major problems for him.

Very true... that's where diplomacy takes a big part. Hopefully a gamer has been trading/communicating with at least one other player where a plan can be arranged to attack the greatest threat... effectively altering the outcome of the game.