Edited sentence: One other improvement of Unreal compared to the previous generation of engines was its networking technology, which greatly improved the scalability of the engine on multiplayer.Probably the biggest reason for its popularity was that the engine architecture and the inclusion of a scripting language made it easy to mod it.Unreal Engine 1 used the Glide API, specifically developed for 3dfx GPUs, instead of OpenGL.Unreal was also the first to use a real Client-server model in the engine architecture