iGridd puzzles are picture logic puzzles also know as Griddlers, Nonograms, or Picross. The result of the solved puzzle is a nice image.
The application comes with 60 free iGridd puzzles. Additionally, there are plenty of iGridd bundles available on AppStore - black and white puzzles, color, mix, and even multis - large puzzles that are formed from several parts of common puzzles and produce a large and detailed image.