Unreal Engine 3 is a complete game development framework for next-generation consoles and DirectX9-equipped PCs, providing the vast array of core technologies, content creation tools, and support infrastructure required by top game developers.
Unreal Swarm is a massively scalable job distribution system optimized for high-speed networks of multi-core PCs.
Developed to power UDK’s global illumination solution, Swarm speeds up the process by telling the computer what jobs to do and when to do them. By delegating the workload, it makes the process of global illumination much faster by transparently spreading out applications over your entire network.
It's a race! who's computer will win?!
Development without Swarm would be like Hall