PC Gamer Castle add-on for SimCity 3000 --------------------------------------- To use the PCG Castle in SimCity 3000, simply double-click on the SC3KAddOnPlug-In.exe to install a DLL you need to install the custom landmark. Then double-click on PCGamer Castle Plug-In.exe to install the building into the program. Then, when you want to create it in the game, simply choose it from the Landmark pull-down menu.