In any Stronghold game, the Keep is always your last line of defence. Stronghold 2 has the additional added bonus of being able to station troops inside the Keep and this was not possible in any game before. There are several Keep types in Stronghold 2, and each one of these are denoted below. Note that if a Keep is not placed on the map by default from the editor, then a Keep is chosen for a player based on who they are. This is chosen in the following way:
It is not recommended to place custom Keeps in Kingmaker maps unless you have fully tested how each Lord responds to it as in some circumstances behaviour can be buggy. Also note that Keeps cannot be destroyed. Once a Lord dies, their Keep is automatically removed from the map and a village flagpole is placed instead. To win the game, you must either kill an enemy lord, or hold an enemy keep.
One tactic which has been suggested in the past would be to move your Lord away from the Keep so that he cannot be killed, however this does not work in practice because if there are no troops on your keep, then once any enemy troops reach the top of your Keep a timer appears. Once the timer reaches zero, you lose the game regardless. The timer starts from 2000. As with capturing estates, the most troops you have stationed on the keep, or the more powerful they are, the faster the countdown goes.
Each Keep in principle has the exact same basic functionality, but some are more advanced, or are more appropriate in specific situations in a game. Each Keep has a hall where feasts commence, and a place where the Lord of the castle is stationed. Below is a breakdown of each Keep type.
The Wooden Keep is the most basic. You can station troops inside and upon the tower, but not on the roof itself. It is also the only Keep type which is Wooden. There is very limited space for deploying ranged troops upon the tower which makes external defence more important when using a Wooden Keep.
The lowest grade of the available Stone Keeps in the game. This Keep does contain a central Great Hall for feasting and most space to station melee troops on the floor of the Keep. It also contains a lot more space on the top of the Keep to station ranged units. There is one small tower in addition to this, where ranged units can also be stationed to provide more of a height advantage over potential attackers.
The second strongest Keep type, this contains significant new defensive structures to help better deter any attacks, including the introduction of a balcony over the Great Hall inside where ranged units can be stationed. This Keep contains much more space inside to station troops, including up the stairwell. On the roof of this Keep, there are four towers, one in each corner which all help to provide an advantage to defenders. There are very strong defensive capabilities of this Keep and sufficient space to be able to utilise them effectively.
The most defensive of all Keeps, this is much larger than all previous Keeps. It contains the same strategic structures inside as the Strong Keep such as a balcony where ranged troops can be stationed, but in addition the space inside means that many more melee troops can be stationed to make a decent effective fighting force.
On the roof, there are four large towers where many more troops can be stationed than on all other Keeps, including a small rear wooden tower and drawbridge. A large number of ranged troops can be utilised effectively on the roof of this Keep. The only downfall to using this Keep type is that is consumes a lot of space in estates so should be avoided within small estates.