iSMatrix is a simple number game: you have to fill a square matrix counting from one, thus using simple rules to choose the matrix next cells.
Starting from number one you can move horizontally or vertically, jumping two cells, or diagonally jumping just one. The target is to fill the matrix cell respecting fixed values.
When you reach a single fixed cell (frozen), you then have to select the position of the next-coming cell, starting from the last number of the sequence. Touching the last number inserted, you can come back to the previous move. It is useful to choose other candidates so to change eventually the solving route.