Bought the alpha, looks like there are going to be several storylines as well as a sandbox mode (didn't try it yet). The only story in the game so far is already impressive and has multiple ways to play out. So far I:
- Got robbed and shot by a fellow survivor who treatened to kill my wive
- Burned the house down, trying to cook up a soup
- Got eaten by the zombies, of course
- Smothered my wife with a pillow

(just tried to give it to her)
- met some other dude then got stuck in the floor trying to rob him blind
Promising start and all. Also the dialogue seems to be actually good in this one.

There is little difference between the tech demo and the alpha so far (implemented clothing for example), but I am already impressed. A lot of clever stuff going on as well, like barricading (seal the doors and the windows or build an actual barricade?), crafting (bandages out of bed sheets, can opener and canned soup to make soup in the oven) and one bit was really cool. I was downstairs making soup and upstairs is a radio transmitting. Unless you are actually upstairs near the radio, you will only catch bits of what it's saying. I like it.