Filled die error? (guessing) Looks like the obverse die had a foreign substance in it when this coin was struck. Probably grease.
I think you're correct. I googled and filled strikes, while they can affect the entire face, are not as drastic looking. Here is a capped die struck nickel. Looks like the same situation.
Late stage die cap strike. Very late in fact. you can see a crack running all the way across the face of the coin. I'm betting the die cap broke off shortly after this coin was struck.. Richard
I posted a picture of a penny very similar to that on CoinTalk a few months back, and that was the general consensus at that time.