Volksy
I love this app. After searching for ages for a simple version of this puzzle (without the fancy graphics, explosions, Ta dahs, etc.) this is it!! If I could suggest one thing I would find helpful - that is, making the unalterable squares stand out a bit - my memory not being quite what it was - would save me having to reset when I forget where they are. Great job! If you bring out a tents and trees puzzle to compliment this one please let me know. I'm addicted to them both. Well done.