Pic-a-Pix or Paint by Numbers or Nanogram Puzzle

Here is Black and Color Pic-a-Pix Puzzle Pack Vol 2 from Conceptis Puzzles, which contains around 10 Pic-a-Pix. Rules and Instructions to play this puzzle is given in this game. 
Once you solve the puzzle, your progress will be saved on your computer. It means that once you come back, you can start the puzzles from where you left it. 

Check out Pic-a-Pix Puzzle Tutorial from Conceptis Puzzle in case you can new to this puzzle.
Checkout Black & White Pic-a-Pix Puzzle Pack Vol.1 which will produce beautiful picture once you solve the puzzle completely.

Also don't forget to solve weekly Pic-a-Pix Puzzle.