From Magican Software:
Magican Rest is a health-care app, which can protect people from overworking. It's also can be used to manage your time. For longtime focusing on work in front of your Mac, you may forget the time and forget to rest. Magican Rest will cover your screen with a countdown, and then you can do nothing but leave it as it is, using the time to rest your eyes, to go around, to be with your family or just nap. And don't worry, everything you did will be remains the same once the resting time is over.