TRICKS :  To start a game, it is important to locate on the grid the cell (or cells) which contains only a single candidate. This single candidate can be naked or hidden. The naked candidate is called ‘’King’’ and the hidden one is called the ‘’Candidate’’. To make game easier, all grids from that website have, at every step of the game, a ‘’King’’, which is the easiest to play.

The KING :

This grid contains a ‘’KING’’ in cell R5C2 or D2C2¹. The ‘K’ shows the cell which can contains only one color. This ‘K’ is with the same color which can be played in this cell. You will notice that, when playing this ‘K’, another ‘K’ is now free‘ in R5C3 (i.e. green color can be played in this cell). To find out a cell which could contain a ‘KING’, we choose a cell and take a look in all its directions (the row, the column and the diagonal(s) if so) and determine which color(s) could be played in this cell. If only one color can be played, it is then a naked candidate : ‘’KING’’ that you can play.

THE CANDIDATE : This grid also contains a ‘’CANDIDATE’’ in cell R4C4 or D1C4². This one is shown by the ‘c’ (orange color) which is the color that can be played in this cell. For each empty cell of this diagonal, we have to check if orange color can be played. We notice that it can be played only in this cell which contains the ‘c’. The verification shows that this cell could also contain the green color. But as we see, the R4C4 cell is the only one on this diagonal which may contain the orange color. It is why we say that the CANDIDATE is hidden.