I'd like to introduce PeerDeviceNet - an android library/components for peer to peer device connection, communication groups management, some high level features which may be helpful for proximal multiplayer games.
It is specially designed for android, works well with network types modern android devices support (wifi, wifi-direct, mobile hotspot), and supports multiple methods for peer device discovery and connection (multicast, NFC tapping, scanning QR code). Its api integrates well with android native apis/designs (idl, intents, messengers)
Its kernel runtime (called Router) is responsible for network detection, peer discovery, device connection management, and more importantly for games, communication group creation, membership management (peer devices join or left), and message routing among devices. The runtime is a pure android/java library project which you can add to your game project directly.
On top of the kernel is the "Core" app which provides ConnectionManager GUI for connected devices and connection parameters, and a PeerConnector GUI which allow you choose network multicast, NFC tapping or scanning QR code as the means for peer discovery and connection initiation. It is a standalone app which you can bundle with you project, so you can bring up ConnectionManager and PeerConnector thru android intents and reuse them for your connections.
There is a few samples: chat, rotate-cube-with-peer, draw-with-peer.
It is open sourced. You can find the source code here:
Prebuilt android apks are here:
More detailed API info:
As a real world test, i developed a "sharing" app allowing a group of devices share pictures, videos, web links and other documents with each other. It is available from google play:
Feedback and suggestions are highly appreciated.