I imagine the Alpha is more to make sure the foundational aspects of the game are good. Moving around on and updating the map, collecting resources and dispersing it amongst the players, updating character sheets, using action points and having the movers properly follow through on it—things like that. We need to make sure playing this gigantic game is even feasible with all the interactions and such going on. I imagine it's going to require a lot of work by the organizers. We need to try to minimize that as much as possible.
Also, we probably need to try to find the right balance in earning electrum through resource gathering, quests, and duels which will directly affect the price of cards and items which may affect some of the skill trees I imagine. I'd guess that the Beta will probably test out the Skill Tree, siege mechanics, and some other secondary features more.