FruityMesh is the reference implementation of the BlueRange initiative. It is the first open source implementation of a mesh network that is based on standard Bluetooth Low Energy 4.1 connections. In contrast to meshes that use advertising and scanning, this allows for a network run with battery powered devices. FruityMesh works with the Nordic nRF51 and nRF52 chipsets in combination with the S130/S132 SoftDevices and enables tons of devices to connect to each other with its auto-meshing capabilities.
Documentation in the Wiki
Documentation is the key and therefore, you should have a look at the wiki to get you started: https://github.com/mwaylabs/fruitymesh/wiki
This project is under active development at the M-Way Solutions GmbH, Germany.
Over-the-mesh firmware updates are currently not open sourced. Interested parties can contact firstname.lastname@example.org to get access to advanced features.