Adventure Quest Worlds is a Free Browser MMO Role Playing Game.
It has a fairly big storyline and a ton of other side quests.
It has a decent player base. Around 20 000 players logged on different servers all the time.
There's an extreme amount of classes to choose from.
The game gets updated several times a week.
This game requires registration and Flash player to play.
You can buy membership for more items and quests.
You can buy Adventure Coins to use for other items. You get some Adventure Coins by buying membership.
Since no one is talking about jmtb02, I guess I should say some of the awesome games he makes.
Some of his games are on armor games, like Achievement Unlocked, AU2, AU3, Elephant Quest, This is the Only Level, TitOl 2, TitOL 3, Coinbox Hero, and much more! His real name is John Cooney, and you can see his bio and games here: http://jmtb02.com/ or on Armor Games. I think the best game he has is Elephant Quest, which is about a blue elephant who goes on a quest to get back his bowler hat from this mammoth called Wooly (It's not as lame as it sounds. It's actually really fun.) Also, try This is the only Level 1, 2, and 3. It's only a level...or is it?
There are quite a few good free to play games on Steam. A lot of these are pretty cool online games, but I'm over 150ms on all of them, so I never get to actually test them out. But if you guys got Steam, go check em' out for some cool free games!