You are a zombie. You didn't mean to be, you meant to blow yourself up, or at least your brains.
First, a brief digression about
zombies and brains. If the best way to kill a zombie is to destroy their brains, why do zombies want to eat brains so badly? Wouldn't that prevent more zombies from being created?
Anyway, this game has no problem with that; removal of a brain doesn't appear to be the end for a zombie (your friend's severed head continues to be moderately talkative even after you've scarfed down the last morsel).
Now you've got a headache and the only cure is brains. And you're fresh out. Time to go find some and hopefully not have your own brains eaten in the process, because, unfairly, the game does end if your brain is eaten. Perhaps you're not dead, perhaps you'll just life forever with the worst headache ever?
The game is mostly puzzles, with the first being an amusing inventory puzzle - you only have two hands (generally) but often need more than that to accomplish a task. Some puzzles are clued much better than others, though, and without the walkthrough I likely would not have solved a particularly harsh timing puzzle involving a busload of zombie children and a nun.
That and the uneven tone are my two major complaints; I can't tell if the game intends to be taken seriously or not. There are several fairly serious and gruesome flashbacks, but the present is full of zombie-flavored physical humor.
Also, that timing puzzle involving school children and the nun? Very frustrating due to insufficient world simulation; the children will follow you, but once they have been in a room due to following you, they never leave, even if they are also in several other rooms. Infinite zombie children!
Finally, the optimal ending, while somewhat romantic, is also intellectually lazy; if the protagonist is so concerned about his own soul now that he's a zombie, why wouldn't he also be concerned about the nun's or the children's souls?
5/10. Some decent potential marred by uneven tone, over-reaching overly complex but insufficiently implemented puzzles but under-reaching plot and character development. Also, a somewhat cruel puzzle which can put the game in an unwinnable, undo-able state if you take too long to realize you've screwed up. Still, fun for the first few bits.