Pressing the Hints-toggle button that appears on the top-right corner slides open the hints control.
The hint button makes the next move for you. There are limited number of hints available for each cipher that you can use without penalty. (In general, the lower your maturity is at the level, you will have more granted. If you are a master, you will have only one before penalty kicks in.) The number in the middle of the button indicates how many you have left for the session. Even if you use them up, you may keep using it. But then the purpose of the session would have turned educational as you will earn only a diminished Doku index. Note that even a single use of legitimate hint will prevent the result from entering the record for the average speed.
The back button erases the previous move. There is no penalty for using it. In hard ciphers, you may occasional make a mistake and continue until you reach an impasse. Then you will need to figure out the first wrong move and delete it and other moves that depend on it. How would you discern the trail of moves you made? Tapping the main board with three-fingers once toggles the view into one that makes your moves distinct from those that make up the original cipher.
The Un-mistake button is more powerful than the back button. It moves back in time just before you made the first mistake. (i.e. it automatically identifies the first mistake you made, if there is any, and erase all subsequent moves.) As this function may be used unfairly in various manner, using the function this way will invalidate your speed record. It is counted as one of your allowed hints. This may be used without penalty, however, if you set a guess mark (see below) on a tentative move you make. (You may want to do so if you cannot come up with a unique candidate to fill a cell. Then you may want to fill it with one color tentatively and follow through its outcome. If the move was not valid, you will soon reach an impasse at which point you may want to cancel the series of moves.) For having the foresight and diligence to mark the guess point, this button then erases all moves up to your most recent guess mark point, without any penalty.
next to Guess Marks and their use
back to Table of Contents