Go Pro!


Begin the game
Game options
Assign Activity


Game Instructions

In this game, your job is to rearrange a set of gray circles in a square playing field, in such a way that the red circles (already on the playing field) all lie exactly halfway between two gray dots. Another way of saying this, every red dot must be the midpoint of a line segment connecting two gray dots on the playing field.

The following image is a simple "Entrapment" puzzle. There are four red dots, and four gray dots.

In solving this puzzle, the first thing I notice is that one of the red dots is against a "wall." The only way to trap this dot is by placing two of my gray dots somewhere along that same wall, on either side of the red dot, and equidistant from it. I decide to try putting my dots directly adjacent to it:

In studying the game board, I realize I can place my next dot in such a way that it traps two of the computer's dots simultaneously:

We're almost finished; we have one more dot to place, and that one dot must trap the computer's remaining red dot. Can you do it? Can you find two ways to place the remaining dot?

Compact Playing Field

In the previous version of this game, the dots were very small, so the entire game took up very little space. This new version was designed with mobile users in mind, so it has much larger dots. Some fans of the game requested that the dots not be quite so big, so we included the "Compact Playing Field" option, which keeps the dots smaller.

Puzzle Hint

Start out by trying some of the "Practice" puzzles. These are all puzzles which contain exactly three red and three gray dots. What you will discover is that most puzzle solutions are built around triangles, so if you can master the easy puzzles, the more challenging puzzles can be broken down into smaller, more manageable pieces. 

Did You Know...

Somewhere on the Entrapment page there is a link to one of our hidden Easter Egg pages, that gives some hints about solving Entrapment puzzles. Find that Easter Egg, and you may get better at solving these puzzles!

Blogs on This Site

Reviews and book lists - books we love!
The site administrator fields questions from visitors.
Like us on Facebook to get updates about new resources
Pro Membership