The demos for PC and Mac listed on the download page contain the first level in Steamalot and a pre-built deck. You can edit the deck if you like, but it will reset for each stage. There is a tutorial in the Mission Select section that is quite handy as well.
We have been working on Steamalot for 3 months and are nearly done with solo play. Steamalot will initially release in a solo play version that includes the story line, card leveling, deck editing, and multiple decks. Muliplayer battles and card trading are underway and set to be out in an update by the end of February 2014.