Just a quick post to let you know that we’re going to be exhibiting at UK Games Expo 2009, in Birmingham on 6th and 7th of June.  Come along and say hello!  There may be some puzzle hints to be had.

You can prebook your entry tickets at the expo’s website, and I understand you can also pay at the door on the day.

There are a few little secrets hidden away in Army Of Zero just because they amused us. This post is about the “easter egg” hidden in the game’s barcode, if you can believe that.

Army Of Zero's Barcode

For any product that you want to put on a shop shelf, you’re going to need to slap a barcode on it.  There are several different formats for barcodes, but the format for retail items is called EAN-13.  The design of this kind of barcode is such that the scanner can interpret it no matter which way it’s passed front of the scanner.

The “EAN” part stands for “European Article Number” (although EAN-13 is actually used worldwide).  The “13″ reflects the fact that the barcode has 13 digits.

All barcoded products have a unique barcode, so not surprisingly, there’s a centralised organisation that hands out codes - GS1.  Their UK website is at www.gs1uk.org.  As a publisher or manufacturer, you register with this agency, and they assign you a block or sequence of barcodes that you can assign to your products as you like.

The number of codes that you are assigned depends on how many products you want to barcode, but the minimum that you get is 1,000 - that’s how many we have, and it’s more than enough for us.

Of the 13 digits in our barcodes, the first nine are proscribed for us, and we’re allowed to choose whatever we like for digits 10, 11 as 12.  Those first nine characters?  Well, the first two or three digits represent the country code (50, for example, represents the UK).  The remaining balance of the first nine characters (”6018516″ in our case) uniquely identify the company or organisation that owns the barcodes.

So that’s 12 digits accounted for.  What about the 13th?

Well, the last digit is a check digit, which helps the scanner to be confident that the scanning worked correctly.  When the item is scanned, calculates what it thinks the 13th digit ought to be, using a defined arithmetic function based on the first 12 digits.  If that doesn’t match with the 13th digit that it thought it saw, then the item won’t scan.  Usually this is followed by the till operator trying again until either the item scans successfully or they give up and enter the product code manually.

For Army Of Zero, we opted for “237″ as the three digits.  As chance would have it, the check digit works out as Zero, which as you know is our lucky number.

But it’s cuter than that, because the last four digits of the barcode are “2370″, which - if you squint - also reads “ZErO”.

Clever, huh?