(We don't tend to run frequent checks on the liveness of these links, so if anyone finds an issue, please report it to the umpire.)
There are many variants on the Assassins game we play here played over the world. Below is a list of Guilds which appeared to be active at the time of writing (October 2016).
If anyone knows of any other websites for active guilds, please inform the umpire on assassins-umpire@srcf.ucam.org.