Version 5.1 has refinements based on player feedback:
The switch to toggle between Fill mode and Mark mode has been revamped, and should be much more responsive now. Also, the header will now change color when in mark mode, so it is more clear what mode you are in.
You'll notice that the grid is now a bit larger, similar to how it was in the older version of Pixelogic.
The hint text size has been bumped up a bit to make it easier to see the numerical clues.
You can now swipe away multiple Xs with the fill tool, along with other improvements.
You may notice some subtle improvements to the menus, transition animations, and win screen.
I'm committed to making Pixelogic the best picross game there is. If you have ideas for more improvements, let me know at email@example.com. I try to respond to everyone.