We actually looked at all sorts of options for this mechanic.
The fundamental is that we don't want players to be immediately and instantly at risk of being literally thrown out of the game (destruction of their only city) as soon as they come out of new player protection.
This left us with the following options:
1. Make the first city built invulnerable to complete destruction by another player
2. Make the last city built invulnerable to complete destruction by another player
3. Allow a player to designate a single city as the capital (invulnerable) once they have a second city
4. Make no city invulnerable except the last suriving one
5. Make the player's first, invulnerable capital city expire its invulnerability after a period of time.
The problem with 2, 3 & 4 is in the siege/blockade mechanics, whereby an attacking player must occupy an empty square adjacent to a city in order to siege or blockade it.
If players can effectively "choose" which city is designated invulnerable (either by methods 2, 3 or 4) then cities clumped together will then make the middle cities in the clump entirely invulnerable to being captured or razed as well, regardless of their capital status, because there wouldn't be any angles of attack.
The issue with 5 is simply that it's arbitrary and we don't like that much either. I guess there's a 5b, whereby players lose invulnerability when they reach (eg) their third city. But somehow I think that's an unlikely circumstance for anyone too near you, Jim!
The way things work currently that it is possible to bombard a player's invulnerable capital city into essentially a husk, but:
a) the attacked player is not forced out of the game and can attempt to seek protection by hiring mercenaries, joining an alliance etc, and
b) the attacking player is forced to expose his armies in a siege encampment should a third party choose to involve themselves in the fray
Allowing a player to build settlers and relocate their city isn't a solution as this simply means that alliance powerbloc clumps of cities will spring up even more quickly and densely as players use the mechanics to force early resettlement.
We'd much rather a player in this situation (who could not / would not / or was unwilling to seek an alternative way out of the situation) abandoned their account and - if they wished to restart on the same server - set up a new account and were randomly assigned to a new starting position as a new player.
To help this process along we will be putting in place a procedure whereby accounts that have not grown in population (or had a player log in to that account) for a period of 3 weeks will go into "abandoned" mode. The player will receive an out-of-game email telling him or her the city has effectively been abandoned, and the city will cease to generate resources. One week later, if there's still no login, the account will be closed and the city removed from the game.
So, Jim, you will still be able to have your part of the centre of the map to call your own if you wish, but we shouldn't pretend that it's not going to involve some unpleasantness for those people who are in the part of the map that you claim - whether it's by forcible resettlement, an account restart, or razing the city to the ground.
(For the avoidance of doubt, we neither condone nor condemn such actions - it's part of the Illyriad sandbox - but we *do* want to make sure that coming out of new player protection isn't an automatic death sentence from more agressive players).
I'm willing to entertain any other suggestions that are better - but please make sure you think them all through and argue them from all perspectives, including potentially exploitable ones.
Edited by GM Stormcrow - 31 Mar 2010 at 17:00