It is responsible for creating individual Sims before you add it to the game. But first, what is a CAS? And what does it do in the game? Create a Sim ExplainedĬreate a Sim, or also known as CAS, is an essential part of The Sims 4 or any game in The Sims franchise. This article focuses mainly on getting more columns for The Sims 4’s CAS or Create a Sim mode.