Hi...
Being sort of curious, I just downloaded BlankBlock, but I believe there's a problem. And no, before you get worried, it's not technical, I believe the game's working fine.
It's about the actual gameplay.
...Quite literally, it's impossible to get only one block left on the board, even in the easiest difficulty. It is all too easy (in the easiest difficulty) to get a row of three, so if your first blank spot is in a corner, it's impossible to finish.
Intermediate and up, I'm not sure, but the concept seems similar so I would assume the same is true.
I would suggest allowing blocks to also be destroyed diagonally or, if you really want to get fancy, perhaps having bonuses of some kind if you destroy blocks in a certain area, time or succession, which would make it more possible to get a score of 1.
https://www.dropbox.com/s/z8ls3rc3f4mkb … n.txt?dl=1