Released a new version with an option to customize puzzle piece shapes used to generate the puzzle. 
Option is available when selecting puzzle - under Customize. For now the UI for it is temporary. 

Also started changing ingame UI:

• Removed Clear board and Menu buttons (menu accessible using Esc key for now)
• Added an option to drag camera using mouse
• Added a boundary for the camera so it does not move out too far
• Small image thumbnail is also draggable now
• Changed zoom indicator to a simpler text label