Time scale
A global multiplier on the game's simulation clock — set it to 0.5 for slow motion, 0 to pause, 2 to fast-forward.
The game multiplies every delta time by a scalar before stepping the simulation, so one knob speeds up, slows down or freezes the whole world. Unity exposes it as Time.timeScale. It powers pause menus, slow-motion effects and bullet time.
The pitfalls are the things that must ignore the scale: UI animations, menu input and real-time networking have to read an unscaled time instead. Fixed-timestep physics needs its step adjusted, and a scale of 0 will crash naive code that divides by elapsed time.