Well, I know we aren't your only fanbase Alex, but I think you may be worrying too much about our execptations for an Alpha release. I think most of us are fairly realistic.
What is the goal with the alpha? Are you looking for feed back, bumping pre-orders, or quelling the B12 beast?
All of the above, really. Thanks for the reality check - I keep not thinking of this as an alpha release.
Feedback we can do, regardless of the state of the game. It seems like any time this community comes across a beta/alpha there are many good ideas, a handful of terrible ones, and many unrealistic ones. Regardless of the value of the feedback, there is always more than enough to keep the developers thinking.
Bumping pre-orders and quelling the beast might be the only areas you run into trouble, as it could be your first chance to run into bad press. If the game is panned and this tread turns into an “I AM DISAPPOINT”, it could hurt your long term preorders/sales.
Now, that being said, very few of the indy games I have seen hyped by this community, even pre-release, turn into majority disappoint at a later point in development. I would suggest you make sure the game tries to meet gaming standards IE buttons, orders, that sort of thing. There should be a “move” command and a “move attack” command. If we right click on a enemy, it should issue an attack order. Basically the game should be playable long before it has 900 weapons and flashy graphics.
It is also important that we (your pre-release customer base) see progress. Minecraft has hit a point where it gets (some) bad press because updates seem so rare now and Notch seems so focused on other projects.
Really, other than those things, I don’t think you have much to worry about, at least from us.