There is a new Game out there which is Drankensang online launched last June, right now they only have 3 characters which is , wizzard, ranger, and barb.
This game runs on Java and runs on a browser, but the graphics is really great IMHO it is almost good as diablo 3 that runs on a browser, so it will run on a chromebook, any laptop with built in graphics card, the thing that caught me on this game is it has a server with pvp on every map, or the non pvp maps you can just enter into duel mode to fight on another player, but off course if he don't accept there will be no fight, I hope there a script writer here who can check the game and make a scritp bot.
Any one who knows how to make a script please try it out, you don't need to download a client anyway, just make sure to check setting and check the box that will improve graphics if you have a 1080p gaming desktop or laptop.