There isn't a specific automated way to create a PowerPoint stopwatch or countdown timer in PowerPoint, so it isn't straightforward. However, you can display a number on a PowerPoint slide and set ...

By installing a third-party add-in to PowerPoint you can insert real-time information that pertains to your presentation such as current weather alerts and forecasts.

One way to do this is by adding snow to a PowerPoint slide. The article How to make it snow in PowerPoint offers a basic snow plan that uses the same shape and random timing effects.