A great collection of categorized cryptogram puzzles from classic literature, Prose & Codes provides a clean and intuitive interface with just enough art to set the mood. Puzzle-solving gameplay is rewarded with thought-provoking quotes + links back to the source material on the Project Gutenberg website. Took me about 14 hours to get all the achievements. The devs have added more than 75 new ciphers (for free) since launch.