http://c2community.ru/forum/viewtopic.php?f=18&t=6900 found this on the Russian community... however i know there is one here but cant find the download link try searching in the completed addons list
also there is this post integration-with-photon-cloud-multiplayer_t70356
and im guessing ur sudden interest in agar.io is because of the upwork project that pays 2000 for a agar.io clone?? you should not do it in C2. since agar.io clones can be found all over internet ...here is one unofficial.. clone on github its limiting ur options for future development.. and being a part of that thing ...
however can be done with a server database create ur own normal server using Ajax with a custom script that saves characters locations... rooms made... etc ... and its done. you can rent a cheap server for startup so u will run 24/7 for a few months at a low cost... later on when ul have .... if u have 200,000 users at same time... you will need to spread the user loading trough a series of servers giving a smooth running ,(service which no photon cloud does for you for free or for cash... cause its to complicated and ul need Staff members).....but ul need more advanced knowledge in php and MySQL but its possible in the end
keep in mind that anything that comes with complexity wont be easy... even if u use a easy to code program... at some point youl need actual knowledge or a skill set in something
PS agar.io its a clone of another game... called Osmos..... which is more awesome... agar.io took the fun out ... of everything... and give it to kids.. to troll my opinion...