Hey Bnx, thanks for sharing your opinion

My goal was to make this game feel as much as a real, mechanical jigsaw as possible. And here I am asking for the opinion of the pro-puzzlers

As for the pieces size the smallest picece I allow is 30x30px and, as you noticed, the higher resolution the higher number of 30x30px pieces possible. Smaller pieces seemed hard to recognize for me. Shadows are calculated according to piece's size.
The game was meant to be played in fullscreen mode as it works on Facebook. There I can take under consideration the most common resolutions and this is how it works:
1. each picture is stored in 3 resolutions (different sizes, different proportions)
2. when you load the game I know what screen resolution you have and I load the picture which is best for you
3. if you have one of the 3 resolutions I targetted - the pictures fits perfectly in your screen
And when you play the standalone version that you played, Bnx:
1. Some area of your screen is taken by browser's toolbars (top part of the screen)
2. Each player has his/her custom size of the toolbars
3. You can scale your browser's window.
4. I cannot predict most commonly used browser's resolutions
5. The image doesn't fit very well
6. The pieces limit is lower
Well... if I succeeded in my murder attempt you are now dead: bored to death...

Sorry about that but you touched the technical side and I couldn't help myself

I will think about your "shuffle" option. As far as I understand it's about puzzle pieces' depths - to change them randomly?
thanks again