There are green spiky cells that split you into about 10 cells if you are large and touch them. I've seen players fall off of the leaderboard due to accidentally touching them.

At the moment you can use a trick to play with your friends (that's what I'm doing): For each player, redirect m.agar.io to your own server (/etc/hosts), which serves a static file with the gameserver location (which you get from the original m.agar.io). Then reload the game until you're in the same realm. Don't forget to set the Access-Control-Allow-Origin header.

+1 for visible borders. How about power ups of some kind? Maybe a speed burst that shrinks you, for example?

The servers restart periodically to apply updates.

I've already answered somewhere in here what it's written in.

I didn't write any math model, I just wrote whatever felt right.

Eventually. Unfortunately not the priority at the moment. You can look at the scoreboard to see if you're in the same server, though.

There are 12 "servers" at the moment (divided among some regions, I think 6 for europe). But each server can host several realms, so I'm not quite sure how many realms are there, but at the very least 12 (probably 30 or more, though). A server can handle up to around 200 players (I don't know the exact number, the CPU is the limit).

The server is written in C++ with libuv to abstract networking (since I test it on windows but the servers run on linux).

See my reply to madeofpalk for the other 2 answers.

cool I just noticed you can turn off skins and names.

Have you tried taking their names? They are not actual bots. They are images provided by the game when you take them, even from popular references like 9gag or Steam.

I have 18 servers running for this game at the moment. If you want to write me a check to pay for all of them, I'll give you my address.

Please don't. It will be filled with rage. ;-)

Emojis or pre-generated text like "close one" would be nice. I think full chat would be too much.