In the following, short tutorial you can learn how your Sim can become a Vampire. It speaks for itself that you need Nightlife for this to work. In the Neighbourhoodscreen, open up the cheat window and enter the cheat: boolprop TestingCheatsEnabled true Enter your desired lot and Shift-click a Sim. Select More... until you see Make Vampire. Simply click that option and your Sim will now be a Vampire. If your Sim is a Vampire and want him/her to be normal again, this option is changed into Cure Vampire: