Unity3d is overkill if you are by your lonesome, taking on the gaming world in your pj's from the confines of your garage.
You can achieve a lot with it, but to build a fully fledged, working, salable product, it is going to need a team, or you better understand you are up against a team or a series of teams.
Starting out, C2 is perfect to gain experience, build a portfolio. No reason you can't use both, because expect 2 plus years for game development with Unity3d at least.
Html5 games is gaining traction. It is invading pc's, mobiles, tablets, readers, and is already in your living rooms.