A friend of mine sent me a link to the Eyeballing Game, presumably because it looks mathematical. At a glance it does look like geometry, but really it is a test to see how well you can recognize when geometric images are correctly aligned. Here’s what the creator of the website (a woodworker) wrote:

Some people are bothered by pictures on the wall hanging slightly crooked. Others may not even be aware that something may be amiss.

If you are somebody who is into woodworking or construction, its good to be one of the people who notice when things are crooked. But I suspect the ability to notice that things might be just a little off square, off centre, or not quite straight, varies greatly. I thought it would be fun for people to try to test their abilities to see if things are straight or crooked in a little game.

It turns out that my abilities in this area are average; that is to say, my scores typically place me near the mode of the distribution.

I found it interesting that some of these problems were quite easy (bisecting an angle and finding the center of a circle), while other ones were quite challenging (recognizing a right angle and bisecting a line segment).