Castle builder or Freebuild is a game mode that is present in the Stronghold franchise.
This mode allows you to build peacefully on your own in a map, freely from any hostile activities. Depending on the size of the map, your limits may be only resources and/or food. Nothing can really harm you, with the exception of inhabitant lions, which attack any living thing that comes near them.
In Stronghold and Stronghold Crusader, several prebuilt events can be triggered when pressing F1. These are:
- Invasions with custom settings. Does not occur if no signposts are pre-placed on the map.
- Setting buildings alight.
- Creating plague clouds around the keep.
- Huge boost in rabbit population.
- Attacks from lion hordes (spawn on map).
- Raids (black macemen) or reinforcements (green archers and a monk) from bandits.
- Travelling fair, marriage and jester (all boost popularity).
- Tree fungus.
In Stronghold 2, F1 brings up an invasion menu, where an invasion can be launched at a given location. You can choose from four different sized armies. After an army size is chosen, a siege tent appears, which can be located anywhere on the map where the tent fits. Upon placement a gray army approaches towards the siege tent and it attempts to defeat you with the help of siege engines and laddermen.
When the Lord is killed either by animals or during an invasion, he automatically respawns a few seconds later. However, in Stronghold 2, when you lose the Lord, so you lose the game.