In The Sims 2 and The Sims 3, most NPCs can be interacted with, at least when they're not on the job, and Sims can build relationships with them.
Sims cannot build relationships with them, and most either can't be interacted with at all, or only have a few interactions that are related to their function. In The Sims, all NPCs, other than the townies, are of this second type. There are two main types of NPC ones that through relationships and/or simple cheats will be able to be playable Sims without any programming errors and ones that were specifically not meant to be played. (While townies are considered to be a class of NPC, they are largely outside the scope of this article.) They are in every Sim game: The Sims, The Sims 2, The Sims 3, and The Sims 4. Non-playable characters ( NPCs) are characters that cannot be played by the player from the game's start.
