Post your favourite Online Game

[donotsow]

What's your favourite online game?
You must also post a link to it.

And by "online game", I mean a flash game you can play in your browser. (Not Minecraft (and don't think that just because I'm saying this it is a good idea to post it))

My favourite online game is Happy Wheels.
www.totaljerkface.com/happy_wheels.tjf

This game is amazing! 

[Strykeroz]

I like Drakensang online, one of my favorite browser games.

[Gumbork]

Hearthstone