For puzzles based around the game 0hno, found at 0hn0.com: a grid logic game in which you must deduce which dots are blue and which are red. Related to the game 0hh1 made by the same people.
The game 0hn0 involves a grid filled with grey, blue and red dots. The blue dots have numbers on them which represent the number of dots they can 'see'.
A blue dot can 'see' any other blue dots in its row or column, but red dots block their view.
To solve the game, you must fill in the grey dots blue or red based on the numbers on the blue dots.
A related game is 0hh1, made by the same people as 0hn0.