Editing 2496: Mine Captcha

In order to prevent automated programs from using web services, Google offers a protection called {{w|reCAPTCHA}}, which performs various tests to see if a user is human or machine. (One of these tests is a "I'm not a robot" checkbox which must be checked in order to proceed, although ticking the box is merely a formality, and later versions of reCAPTCHA can simply perform the tests quietly in the background without needing user consent).

If the reCAPTCHA system suspects that the user may be an automated bot, it presents an image recognition challenge that only humans should be able to pass. This has the desired effect of denying access to robots, but it also has a side benefit that the human input can be used to train Google's image recognition software. The challenge usually features a square grid of images, typically things one might see while driving - eg. "check all squares containing a STOP SIGN". If the user clicks the correct squares, they are permitted to continue.

{{w|Minesweeper (video game)|Minesweeper}}, on the other hand, is a logic puzzle game in which the player is presented with a grid of unrevealed squares, and must deduce the location of mines that have been secretly hidden on random squares. The game provides clues by marking some squares with the number of mines (up to a maximum of 8) that are adjacent to that square; by carefully considering the possibilities, a player can deduce which squares must contain mines, and mark them with flags to avoid clicking on them. Revealing a mine loses the game.

In this comic, Randall combines the two concepts to create a "Mine Captcha", which is presented in the form of a reCAPTCHA challenge but actually appears to be a mini game of Minesweeper. (To be more precise, it is actually the opposite of regular Minesweeper, since the challenge invites the user to click on the mines - in Minesweeper, you are supposed to ''not'' click the mines. Furthermore, on its own terms it is unsolveable as a reCAPTCHA, since the user is asked to click on all ''pictures'' of mines. However, as in the real Minesweeper, there are no pictures of mines displayed (in Minesweeper, these only appear when the game is over). Taking the game as playable, however, in both cases you still need to know where the mines are, so it is still solved the same way).

Another issue is that games of Minesweeper can sometimes involve a degree of luck, as it is possible to generate a puzzle which does not give sufficient information to unambiguously deduce the location of every mine (Though this may not be a problem since Randall's Minesweeper is only a 4x4 grid). In these situations, the most a player can do is click the uncertain square and hope for the best. If the Mine Captcha is poorly implemented in this way, this would increase false negatives in human detection due to some humans failing the captcha purely due to bad luck. (Some variants attempt to eliminate this problem: ''[https://pragmada.x10hosting.com/mindet.html Mine Detector]'', for example, is a variant game which provides better information, such that it's almost always solvable without guessing except at the highest difficulty level).

Finally, a Mine Captcha would actually be fairly easy for an artificial intelligence (AI) to solve, since it is a logic puzzle - as long as the AI can read the numbers, it can simply use an algorithm to eliminate all impossibilities until it has the correct answer. (Indeed, for a 4x4 grid, it's even easier than that; a computer could quickly brute-force the problem by trying every possible arrangement of mines until it has the correct one).

*The solved puzzle as it would look if played as a real minesweeper game, except the mines would be represented by flags. (The empty square top right corner has 0 bombs next to it. This is not written in the game but indicated as this field has been pushed down):