You're launching GPS satellites into space. They need to orbit the earth in the correct order. But your launch windows are limited. You can only launch satellites where the spinner points each turn. It is your job to pick the best satellite for each launch to get your birds in order before your opponents.
GPS is a game about how fun it is to spin that spinner. And it is a very satisfying spin.
It is a game about rooting for the rocket to land on your number.
GPS is a game about putting yourself in a position where the spinner is most likely to help you.