Google Play Games can now utilize "Nearby" multiplayer if implemented by the developers. Nearby multiplayer allows users to invite other players who are near them in real life to their online game session. It also can find people playing the same game as you who are close by.
Games that take advantage of this feature will be able to alert players when someone is playing a game you have nearby. App developers have to use the latest Google Play Games API in order to take advantage of this feature.