Create-A-Sim (CAS) is a cornerstone feature of The Sims 4 which allows players to personalize their virtual avatars with an array of hairstyles, clothing, and accessories. Many players find that they spend the majority of their time in CAS designing unique characters and recreating their friends and family as Sims. Staring at the standard blue-green screen background for hours on end can get boring, so players should consider downloading custom CAS backgrounds.