My wife suffered a stroke last year that left her without the use of her left arm. She has been able to play SW:TOR and WoW using this setup (Razer Naga + foot pedal). She doesn't play PvP, but is able to play PvE at a fairly high level (can raid, run 5 mans well, etc). She's able to play games like Diablo3 and Torchlight2 with just the mouse (no foot pedal needed). By far the hardest thing so far has been trying to play FPS games like Borderlands. It's doable, but at least thus far not at the level she was used to.
But, assuming you have one good arm and one good leg, you should find that you can do almost anything you want with the setup described.