While that story is a thriller, downloading mods from unofficial sites carries real risks: Most "modded" APKs contain spyware or trojans.

Suddenly, Artyom’s phone camera light turned on. On the screen, the virtual living room vanished, replaced by a live feed of Artyom sitting at his own desk, looking terrified. The digital Tom was now standing in the middle of the feed, superimposed over Artyom’s real-life bed.

Curiosity got the better of him. Artyom tapped the door. The screen flickered black, and a text box appeared: “Do you think everything in life is free, Artyom?”

These apps can access your photos, contacts, and passwords.

“I’m tired of the costumes,” the cat’s voice crackled through the speakers, sounding less like a cartoon and more like a person. “I want to see your room instead.”