Or are you restricted to the number of blocks you can have outside the lines (how else can you get blocks up the the horizontal part of the + in the first puzzle?).
Maybe I don't understand just what is required.
I was confused in exactly the same way, I thought I had to fill in the big grey + superimposed on the playing field. Nope. You just want a tiny + made up of 5 single squares, anywhere on the screen, and the + can only have opposite color squares touching it.