While all games of this period supported 16-bit color, many were adopting 32-bit color (really 24-bit color with an 8-bit alpha channel) as well. Soon, many benchmark sites began touting 32-bit as a standard. The Unreal Engine, used in a large number of FPS games since its release, was an important milestone at the time. It used the Glide API, specifically developed for 3dfx GPUs, instead of OpenGL. 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. 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.