An interesting take on the Picross formula, Keaton.com's CoinCross tasks players with placing coins on a board to match the total amount shown in the first cell of every row and column. Coins range from one to five hundred yen, and you can use any combination of loose change to solve a given puzzle.

The best way to go about placing the coins is to begin with rows or columns that have the least number of cells. They're much easier to guess, and once you've figured them out, you can start to work your way up (or down, or sideways) from there. The colour of the hint number will also change to pink whenever the correct total for a row or column is achieved.

Coin Cross is a free download from the App Store. Some of the harder puzzle packs are offered as in-app purchases, but around fifty standard puzzles can be accessed from the get go.