Day 599: All About Exes And Ohs

originally published August 21, 2013

Back in the 1980’s, we learned that the game of Tic-Tac-Toe has the ability to disable the United States government’s most powerful military computer system. Matthew Broderick taught us this, years before he educated us all about the benefits of truancy, auto theft, dishonesty, and impersonating a sausage king.

In case the reference to 1982’s Wargames is a little too antiquated for your tastes, here’s what happened. A proto-geek-chic kid (Broderick) hacks into this military computer and accidentally sets it to launch the American stash of thermonuclear weapons. The only way to disarm the thing is to set it on a Tic-Tac-Toe loop, playing against itself only to discover that with two perfect players, there will be a draw every time.

So why play the game at all? Is there no way for two intelligent, focused people to enjoy some cerebral competition amid the enlarged intersecting grid of a phone’s pound key? Actually, no. If you lose at tic-tac-toe, that means you probably stopped paying attention. That said, there are strategies you could employ to trip up your opponent. But the real question is, why bother?

Tic-tac-toe is a pastime, a game whose only purpose is to teach kids the art of sportsmanship and to see whose head is higher up in the clouds, disconnected from reality. Perhaps it has always been this way.

There are tic-tac-toe markings all over the remains of the Roman Empire, and evidence suggests that a variant of the game may have been played back in the first century AD. This game would have been more like Three Men’s Morris, in which each player only gets three pieces, then has to move them around the board to get them in a straight line. The game as we know it didn’t develop until later, possibly until the 19th century. I say ‘possibly’ because while we can pinpoint the game’s first appearance in literature (1864), we really don’t know how long it was lingering in the culture before Anthony Trollope dropped ‘tit-tat-toe’ into his novel, Can You Forgive Her.

We can say with some degree of certainty that the game went by the name ‘noughts and crosses’ until sometime during the last century. It still goes by that name in Great Britain, Ireland, Australia, New Zealand and South Africa. Up in Northern Ireland they call it Exy-Ozys for reasons that probably involve whisky. X’s and O’s is another common name for the game, as is O-X if you live in the tiny island nation of Mauritius. I suppose there are some who call it Celebrity-Free-Table-Top-Hollywood-Squares.

So if this game is theoretically unwinnable, why bother with a strategy? Well, as I pointed out, you can still catch your opponent asleep at the wheel. You’ll never earn any endorsements by knowing tic-tac-toe like the back of your hand (or, I suppose, your toe), but I’m sure you know someone you can impress with this knowledge.

First off, there are only 138 possible outcomes to the game. That’s 138 arrangements of the X’s and O’s on the board if you eliminate symmetries and rotations. Assuming X makes the first move, there are 91 possible positions in which X wins, 44 in which O wins, and only 3 that are draws. That’s right, all those tied games you’ve tossed into the heap over the years will work out to one of three arrangements of X’s and O’s, assuming you rotate the page as needed.

As for the actual game process, there are 255,168 possible games that can occur on a tic-tac-toe board. 131,184 would win for X, 77,904 would win for O, and 46,080 will end as a draw. Again, this assumes X goes first. You want to win this game? Go first.

When looking to slash that first X upon a blank board, instinct often propels people to make their first move in the center square. This makes sense; from the middle you can stretch in any direction to form that winning trio. But while you can still pull off a win with this strategy, your best first move is to drop your X in the corner. The key to the game is forming a ‘fork’. This is where you have two possible winning moves and your opponent can only block one.

If you start in a corner, and an O gets placed in another corner, you’ve won the game. Just take a third corner (O will have to block between those two X’s), then the fourth corner. You’ll have two potential winning moves and your opponent will feel like a grade-A schmuck for losing a game no one is supposed to lose.

Sometimes you’ll find yourself swooshing O’s instead – for the purposes of this article that means you start second. Don’t worry, you can still hold your own in this bloodsport of crisscrosses and death-rings. If X takes the corner spot, grab the center square, then a side middle. This will eliminate the possibility of X getting a fork and forcing the win. Taking a side square first will leave you open to losing if your opponent knows what they’re doing.

If X starts out in the center square, grab a corner – a side square should never be your first move. Unfortunately, there doesn’t seem to be any solid strategy for winning if you start second – just try to be the first to grab three corners if you can.

There are a number of variations to this simple game, like 3-D tic-tac-toe, which features only one significant strategy, and that’s to grab the middle square. Tic-Tac-Toe Chess is an odd amalgam of the two games, in which you are allowed to make a mark on the tic-tac-toe sheet only when you capture an opponent’s piece. This creates a very defensive (and aggravating) game of chess, since losing three pieces in a row will give your opponent three consecutive turns on the tic-tac-toe sheet. Assuming your opponent isn’t an idiot, they’ll probably win with that.

Some people make larger boards and try for more X’s or O’s in a row to win – though at that point, you may as well just invest in a Connect-4 game. Suicide tic-tac-toe is the same as the original game, but the first player to get three in a row loses the game. I can’t help you out with strategies for that one.

As one of the only universal table-top games, primitive enough to be playable with a rock on a prison cell wall, yet simple enough to transcend language and cultural barriers, I don’t suspect this game will disappear anytime soon.

And given that tic-tac-toe may someday save humanity and avert a large-scale nuclear war, I guess that’s a good thing.

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