Sims 4 pets transformed into humans by old Cats and Dogs bug

pcgamesn.com:

Sims 4 pets could transform into humans thanks to a weird and wonderful bug in the Cats and Dogs expansion, explains one former EA Maxis employee, who spotted the glitch while working on the classic life simulator.

Sims pets are apparently subject to a programming routine called a “walk-by”, which also applies to human, NPC Sims, and determines what behaviour they will perform whenever they load into a world – when a pet or an NPC Sim first loads into an environment, the walk-by is what instructs them to start talking to someone, explore the environment, use a certain object, and so on. For the Cats and Dogs expansion, EA Maxis added an additional walk-by for when NPC Sims would bring their equally NPC dogs to the beach, the idea being that, like the human Sims would start walking around and exploring the world, so would their pets.

However, despite this innocent and adorable premise, something strange and horrifying started to happen. When arriving at the beach, players could observe several NPC Sims standing still, doing nothing, refusing to move or leave, regardless of their health and status bars – they would simply stand there, silent, waiting to die. There was something deeply wrong with them. As the former EA Maxis designer who spotted the bug explains, these human Sims had somehow replaced other Sims’ dogs, and become infected by their programming.

“For Cats and Dogs, we added a dog-walking walk-by, where a Sim would take their dog for a walk,” writes Anora Albert, who now works as a technical designer at Destiny 2 creator Bungie. “I noticed a Sim would sometimes spawn in, and wouldn’t move or leave, even if they were starving! After digging into it, I found that these Sims were getting spawned in by a dog walker