Ask HN: What are some online multiplayer game like agar.io and curveferver

These are commonly known as ".io games" after the ccTLD (though not all have this type of domain). There is a subreddit dedicated to them where a large number of them can be found: https://www.reddit.com/r/IoGames/

Very different but check out Neptune's Pride. http://np.ironhelmet.com

Might want to check here: http://iogames.space/

http://slither.io/ is a good one.

Slither.io

My current favorite!

generals.io

We've been playing this one at work, it's great. Even joined a tournament a few months ago.

The bots haven't taken over?

No, there's a separate bot server.

https://play.freeciv.org

slither.io is a great one that's probably as popular as agar.io, but since you didn't mention it I thought I'd throw it out there.

slay.one _ played it since day one, they are getting on steam greenlight soon

splix.io