The paper presents the project and the development strategy of a continuously operating high-flux (>1018 n s1-) fusion volumetric neutron source. The proposed facility is based on the gas-dynamic magnetic plasma confinement device with high-power (∼50MW) neutral beam injection. Project roadmap includes construction of several prototype installations addressing a specific set of physics and engineering problems, starting from the continuous operation of critical subsystems and ending with advanced plasma physics problems specific to axisymmetric mirror-based plasma confinement machines. The project aims to build the widest possible international collaboration to create a multi-purpose experimental facility, which could solve a set of problems most critical to deployment of economical fusion power worldwide. The paper details on the core principles of operation of a gas-dynamic neutron source, presents the parameters, expected performance and basic construction principles of intermediate and final devices, and outlines the ways to resolve the scientific and engineering challenges that constitute the project.