Backdoor

A backdoor attack is a strategic attack done by a player to attack an enemy through the "back door". There is some controversy amongst bigger players whether they think it is alright to do or if it is a kind of cheating move.

Method
A backdoor attack is done like this:
 * 1) A player is trying to attack an enemy city. However, as the gates are closed, he cannot get at the troops inside.
 * 2) The player finds a city that the enemy has colonized.
 * 3) He attacks the colony instead. As most big players do not bother changing the suppression setting, when he attacks, the troops in the enemy city which are set to guard the colony try to defend the colony, thereby being able to be killed.
 * 4) All the player has to do now is repeatedly attack the colony until the troops in the main city have been killed off.

This is why it is important to set suppression setting to 0 if you do not have relatively many troops in your city. And even then someone could come and backdoor your city, and there you are without any troops.