Thought I'd post this here rather than on computers.
If you haven't already got it, This is a really good game/puzzle for tablets.
You follow a grid to fill in squares with either black & white, or colours, and it makes a picture
It's free, and there are often updates with more puzzles.
They're arranged into simple/small/large/coloured/advanced, so it's easy to learn.
It's how I pass the time if I'm up really early, and sometimes am too tired to concentrate on reading.
Some of the puzzles have squares that are too small to manage on a 7" tablet, but there are plenty there - nearly 300 I think