Uncross the Leylines - A solo puzzle game to play while you wait
Uncross in Leylines is a minigame from World of Warcraft in which the goal is to untangled all the lines. You do this by using Primary Fire on 2 of the point, swapping their position.
The levels start off easy but get progressively more difficult. There's currently only 8 levels. I estimate it takes about 15 minutes to complete, making it a perfect minigame to play during one of your DPS queues.
Each level has an intended finished shape, resulting in a satisfying shape. Some levels can be solved in multiple ways, all of which are perfectly valid.