## Introduction: 4DOX (Four-dimensional Noughts & Crosses)

Are flat board games too old-school?

Do three-dimensional moves not tax your brain enough?

Do you want to out-geek your friends?

Time to take noughts and crosses ("tic-tac-toe" for our colonial cousins) into not just three dimensions, but four.

Four-dimensional noughts and crosses.

I call it "4DOX" for short...

Disclosure: I first encountered four-dimensional noughts and crosses in a tattered second-hand copy of a book of "mathematical diversions", about 30 years ago. The book is long-gone, and I can't remember what it was actually called. If you think I have broken somebody's copyright (yours?), then please let me know so that I can give the original creator proper credit.

## Step 1: The Playing "surface"

Mathematically, 4DOX happens in four dimensions, but you play it on a two-dimensional surface.

The playing board is a 4x4 grid of 4x4 grids.

Still confused? Meh, just print out the sheet...

## Step 2: How to Play

As for normal, two-dimensional noughts and crosses (2DOX), players take turns to mark a square, trying to form up a line of four.

At the same time, they are trying to block the other player from forming their own lines of four.

A winning line of four can take many forms - the image above gives just a few winning lines - but the easiest way to tell if a line is correct is to picture the four smaller grids as if they were stacked up in the order they appear on the sheet. If the marked squares make a straight line in three dimensions, it counts.

A big advantage of 4DOX over 2DOX is that there is space for more than two players, so you can play as a group around table, in the coffee shop, down the pub etc.

The easiest way to include more people is drop the "O" and "X", and switch to players just writing their first initial in the squares.

## Step 3: Alternatives and Extras

Because there is a lot of "space" in a 4DOX board, you don't have to stop playing when the first person gets a line of four.

You can keep playing for as long as you like, then count up how many lines each player has got.

You can also add any "house" rules you like, such as making the first line worth two or three points instead of one.

To help you out, I've also made versions of the file with different numbers of the board on it.

• "4DOX2" has two A5 versions of the original board on one A4 page.
• "4DOX4" has 4 boards arranged on an A3 page.
• "4DOX4s" is the same as 4DOX4, but reduced to A4 - that way, you can print the board at home, and photocopy it larger at work or school.

You can make the board last longer by laminating it and playing with a whiteboard marker.

Of course, you don't have to restrict yourself to playing on printouts of my version of the board - you can sketch it out on scrap paper, scribe it carefully on graph paper, or scratch it into the dirt of the playground.

Share with your friends, have a play, and enjoy!

### Attachments

Participated in the
Summer Fun Contest 2016

Participated in the
Maker Olympics Contest 2016