A newer entrant to the burgeoning riddle puzzle genre would be Stump Riddles. The twist on this app is that they take your puzzler question and play with it visually. Words, numbers and letters are incorporated to each level, as well as a nice graphic icon.
The size of the font might be large or tiny. A word or letter might be uniquely placed on the screen to hint at a hidden word or meaning. The functionality of this mobile app, combined with the seemless user interface puts this game ahead of the competition, in my opinion.
As you complete each level, you earn coins. The virtual store lets you use your coins to grab boosts. 60 coins will get you the Reveal A Letter boost, which gives you a clue towards the answer. If you spend 90 coins, you can get the Remove Letters boost, which will trash all letters that aren’t used to solve the puzzle. If you get frustrated and you just want to use the Skip The Level boost, you can purchase that with real money for $0.99.
If you are like me and really try to avoid the coins or virtual store, altogether, be sure to check out one of the cheat sites online. I prefer to use Stump Riddles Answers for my sleuthing. I like the way they have their database setup and all of the levels are sorted in a user-friendly sort of way.