The Castle Generator needs Blender 5.2 or newer. Install the generator ZIP under Edit > Preferences > Add-ons > Install from Disk. Generated castles export as glTF or FBX with the Export Castle button, so you can bring them into Unreal, Unity, Godot or any other engine. Ready made engine versions of the kit (Unreal Engine 5.8 project, Unity URP package, Godot 4 folder) are sold separately on Fab and itch.io.