This is a pretty awesome game. It seems like Magic the Gathering, a game I tried to get into but it never made sense to me.

My only problem with it was getting eased into the game. The tutorial works but I just skipped over all the text and tried to understand how it worked. Playing the first easy game helped but some things didn't make sense to me, like I wasn't sure exactly what the numbers on the cards meant. By playing a second game and actually reading the help clarified my confusion.

At the very least, you should add a "help" button to make a pop-up window with reference on how the game works. Ideally, I'd like to have some kind of animated demo that made me understand what was going on visually, or at least some indication of what cards are attacking what. I was confused as to why my player has HP as well as the cards.

I would suggest adding a "guest" account that lets you start playing right away. The only reason I bothered to play was because tonypa posted a login. The title screen doesn't even let you know what kind of game it is so there's nothing compelling enough to get people to register in the first place. Maybe you should post a demo video or some kind of demonstration to get someone interested if you want to make login mandatory.

I'd like to see a multiplayer version with a lobby and whatnot. Could be fun!