- Open your Settings app.
- Click Apps.
- Look for Google Play Games.
- Click Google Play Games.
- Click the Force Stop, Clear Cache, and Clear Data buttons, in that order. Hopefully they will gray out. If not, go around again several times. Eventually they should gray out. (While taking these screenshots I had to go around twice.)
- When all three buttons are grayed out, go on to the next step.
- There should be a button labeled either Uninstall or Uninstall Upgrades. Click it.
- After the uninstall is complete, open the Google Play Store app and install the Google Play Games app. It may be the same version as you just uninstalled, but that's okay; the point is that it was installed from a clean slate.