(...or CNPS as afficionados call it) is an extremely simple game. The aim of CNPS is to spot every number on the conventional old-style UK car number plate, in order, from 1 to 999. Simple. Easy. Addictive. You have been warned.
The official rules of CPNS are here, on the Richard Herring website. They're well worth a read. Richard's been playing the game for six months, and so far he's got as far as 120. Here's a report explaining how he started, and here's a report from six weeks down the line, still struggling to find number 16.
I must confess that I've played this game too. I started at Christmas 1995 by spotting a 1, then spent an entire two-hour car journey completely failing to spot a 2. "Surely," I thought, "Surely it can't be that difficult to spot a 2." And I was hooked.
The numbers from 1-20 are always the hardest to spot because for the last twenty years they've only been issued on personalised number plates. In fact it's the numbers from 10-20 that are the hardest to spot because they're the personalised numberplate numbers that nobody really wants. After 20 it gets easier, but not much easier.
On average, you should spot each numberplate number approximately once in every thousand(ish) plates. Things rarely work out averagely though, so sometimes you spot the next number within minutes of the last, while at other times you may suffer from week after frustrating week of desperate non-appearance. Even worse, you keep on spotting the number after the one you really want, just when you don't need it, then lose sight of it completely as soon as you do finally need it. Go read Richard's stuff - he's been there. Overall the game should require sight of about 10002 = one million cars to complete. It's definitely not a commitment to be undertaken lightly.
It took me almost four years to progress from that initial 1 to my final 999 (which was on an F-reg Landrover on the A14 just north of Ipswich, if you care). I'm glad I finished before I moved to London, because I see far fewer cars now on my daily Underground commute. I'm also glad I finished before they brought in this new numberplate numbering system. Sure, 01, 02, 03... may be a much easier start, but the rest of the game is going to get a whole lot harder as three-digit-number plates become a thing of the past.
If you're interested in playing (go on, it's not as sad as it sounds) you can sign up here on the CNPS website. Compete against other players and try to get on the leaderboard. It's more interesting and addictive than it sounds, honest. Just don't expect to finish any time soon.
As Richard says: As a CNP Spotter you must abide by the CNPS code. "I promise to do my best at spotting numbers consecutively, to do my duty no matter how boring and to never, ever cheat in the game or lie about where I’ve got up to, because I will only be cheating myself in the end." Say this out loud before you start and at any point when you feel you are tempted to cheat or stop playing because the game is rubbish.