I'll do a dungeon or two with you. Love that game. It is, however, an online RPG, meaning they have ways of trying to get you to pay. The limited energy thing is bad. Also, the auction system of players buying stuff is great, because you can find good deals if you have the time, but bad because it allows the players to determine the price of things.
My example of this is
http://www.puppetguardian.com. I played this game while it was in beta, and the prices of things were reasonable. But soon, people started buying in game money, and it threw the entire market off. Soon everything was too expensive. Inflation is bad enough in real life, but in a video game...
Still a fairly fun, free game. (Most people only play it for the hat in TF2 though.)