Instant Action has several 3D multiplayer online games, in different genres, that you play in your browser. It's supported by micro transactions, but it's all optional. The games are pretty fun, but unfortunately people barely play some of them. Almost everyone plays the FPS. Quake Live is Quake 3 Arena that you can play in your browser for free. It's supported by ads. The game runs flawlessly, and I've had no lag at all. It even has a skill matching system determined by your performance in the tutorial.