Hercules is a free and open source implementation of Aegis, a Ragnarok Online game server, and is written in C. Written in C the program is very versatile and provides NPCs, warps and modifications. and is currently version controlled via Git. The project is jointly managed by a group of volunteers located around the world as well as a tremendous community providing QA and support. Hercules is a continuation of the original Athena project.
Hercules is available via Git