Language
Some players have seen other players with inappropriate names such as 'F word you.' Kids should watch what they write down because then other people could see it and personally I would be embarrassed and you could get in trouble. It is also not nice to use bad language because it could encourage young children to say the word or do the same. And last but not least, there is no reason to had bad words as you name in Agar.io, if you think it attracts people, it does, in a bad way. They would say "OK! that's inappropriate!" And cover the word up with their hand.
Playing
Try not to play ALL day long just to get in the leader board! I know that it is addicting, some people will play for hours just to get on the leader board. Besides, to much screen is bad for you if you are not doing anything. Also, don't play Agar.io during school unless all your work is done or your free or something. Agar.io is fun, but it can take up your time so you might not finish your homework.
COLORs
The colors are always annoying. You cant pick or draw a background with out signing in though. When you go on the game there should be a button that says 'login and play' with a Facebook sign on it. To do that, you need a Facebook account. you sign in with Facebook to get your own customized backround
Dancing Beauty
The player of Dancing Beauty is still a mystery.