The Global Agenda game for PC is pretty sweet and they just made it permanently free to play.
Global Agenda is basically a a free-roaming FPS with aspects of an RPG.  For example, your character levels and unlocks better weapons during your gameplay.
I played Global Agenda back when the game was free, but you could only play to a certain point.  At that point I forgot about the game because they wanted money to level further.
But now Global Agenda is totally free to play.  There is an option for a one-time fee of $20, which makes you level faster and unlocks a few pretty cool features that you may or may not want.

Try out Global Agenda now, or as soon as it's totally free.
But you can always download it now.  I think the level cap is around 20 or so to start with.