Otteretto is a puzzle game where you match blocks to make palindromes. Rather than the usual match-three format, instead you have to find patterns that mirror in the middle, like a palindrome but with colours/shapes rather than letters.

Play involves using the mouse to highlight a series of blocks in the well. Your aim is to create long strings of colours that form the aforementioned palindromes. This starts simply, but soon leads to strategic selection of shorter palindromes (sometimes just a single block) to setup longer strings.

There are different modes. Classic challenges you to achieve a particular score with a limited number of blocks, to be able to move on to the next level. Daily Stack is a global competition where you try and score more points from the shared starting point that day. The puzzles are hand crafted sets of blocks that require you to find a single, massive palindrome. Containment challenges you to avoid the well filling up by finding long palindromes as more squares are added every move. Walls challenges you to find palindromes around each level's impassable walls.

The result is an unusual and elegant puzzle challenge. The daily challenge and other modes extend the play of this highly polished game that innovates what was quite a tired genre.