Although most view tic-tac-toe as a kid’s game, puzzle designers see it as a canvas. I think the game’s simplicity almost taunts people—is a 3×3 grid with only two possible symbols really going to stump you? Yet members of the puzzle community continue to devise ingenious little twists to keep the game fresh and challenging. The second puzzle we ran in this series was based on tic-tac-toe. I recommend checking it out if you missed it, because it has a wonderful premise.

With perfect play, tic-tac-toe always ends in a draw. But what if you can play for both sides?

Did you miss last week’s puzzle? Check it out here, and find its solution at the bottom of today’s article. Be careful not to read too far ahead if you haven’t solved last week’s yet!

Puzzle #43: Anarchy Tic-Tac-Toe

You and I will play a game of tic-tac-toe, and you’ll go first. Instead of you always placing an X and me always placing an O, we’re both free to place either symbol in any open cell on our turns. The first person to create a three-in-a-row of either type (XXX or OOO) wins the game.

Which one of us can force a win and how?

Most tic-tac-toe puzzles can at least be solved through extensive trial and error, but the good ones don’t require it. While tinkering with diagrams will help you gain intuition, you shouldn’t need to fill your notebook with them.

I’ll be back Monday with the solution and a new puzzle. Do you know a cool puzzle that you think should be featured here? Message me on X @JackPMurtagh or email me at gizmodopuzzle@gmail.com

Solution to Puzzle #42: Grammatically Correct

In what might be a first, we had no fully correct submissions to last week’s grammar quiz. I guess the puzzles buffaloed you all.

Punctuate the following so that they make sense:

1. that that is is that that is not is not is that it it is
2. James while John had had had had had had had had had had had a better effect on the teacher

1. That that is, is. That that is not, is not. Is that it? It is.

In other words, “Everything that exists, must exist. Everything that does not exist, must not exist. Is that all I have to say? Yes.”

2. James, while John had had “had,” had had “had had.” “Had had” had had a better effect on the teacher.

For this one, imagine that James and John both took a grammar test in class. One of them used “had” in a sentence, like “Mary had a little lamb back when she was a child,” while the other used “had had,” as in “Mary had had a little lamb back when she was a child.” The teacher preferred the latter. In our punctuated sentences, the words in quotes represent what the boys had written on their test.

Below, fill in the three blanks with the same letters in the same order so that the resulting sentence makes sense. You may add spaces between letters as needed:

The ____ doctor was ____ to operate on the patient because there was ____.

Answer: The notable doctor was not able to operate on the patient because there was no table.

Divisible by Zero made an interesting case for the word “good” fitting the sentence as well. They write:

The good doctor was good to operate on the patient because there was good.

“good” as in skilled or moral, “good” as in willing, and “good” as in “There was good. There was bad. There were things in-between.”