BeGone is a free to play online first person shooter. It may only feature one map, but it's playable from your browser if you install the Unity browser plugin.
There are lots of options when it comes to online FPS games, but BeGone is unusual as it's browser based. Unity allows BeGone to have impressive graphics: This is no Call of Duty, but it looks surprisingly good. You can change the camera view from first person to third person, which exposes the average animation of your character. Sound is pretty average, limited to environment noise, gunshots and groans.
A game of BeGone can have up to 12 players, in two teams. You spawn at on end of the map, and simply have to move around trying to kill the opposition, while not being shot yourself. Kills win you money, which can be spent on better weapons. This of course means other players may have better guns than newbies, and there seems to be no way to play in "expert" or "newbie" games.
While the game generally runs smoothly, there are sometimes moments when the frame rate drops, most often when you are being shot at, which is annoying. This is made worse by some bullet animation disappearing sometimes - you will feel you are being shot by an invisible hail of bullets sometimes! Hopefully these glitches will be ironed out, as without them BeGone would be an enjoyable, if not very deep multiplayer shooter.
BeGone is impressive for a browser game, but in the end feels old fashioned and buggy compared to 'real' action games. It's perhaps a signal of the quality of browser game we can expect in the future, but it's not up to scratch yet.