There’s a copy of me running around London. It runs at the right speed, but it’s unstuck in time: unstuck by 365 days, in fact.

Tom Armitage In The Past is a foursquare user. He checks in where I was a year ago. He says what I said a year ago. As long as the game systems haven’t changed, he gets the badges I got a year ago. (And, if the game rules do change, he’ll start to deviate from me).

He’s maintained by a piece of software I wrote called ghostcar.

In racing games like Ridge Racer, your previous time attack high score is often represented by a 3D outline of a car rendered into the same world as you – a “ghost car”. Matt Jones reminded me of this at the pub one night, as I explained my idea, and the project had a name.

It’s not a spambot. I’m its only friend; it’s invisible to people who aren’t its friend. It’s invisible to venue owners – ie, it’s not generating false marketing data. Honesty is Foursquare’s main currency: saying where you really are, being who you really say.

I’m not breaking the terms of service. When I wrote it, the Foursquare terms of service told me I couldn’t impersonate other people.

But I’m not impersonating other people. I’m impersonating myself. That’s got to be OK, right?

So: why did I do this?

There were two main inspirations. Firstly, James Wheare’s Twitshift (now sadly closed). Twitshift works because its output is in the same medium as the source data. I didn’t warm to Timehop because it was just an email. Email is good, and there’s value in juxtaposition – but anyone can send an email. Email dilutes the notion of “being”, however. Foursquare is not, precisely, about presence – it’s just about saying you were somewhere – but email about foursquare feels like another abstraction layer. I wanted to minimise abstraction. And so, to do that, I’d need to build a Foursquare timeshifted-echo service that itself output to Foursquare.

Secondly, I remember Kevin Slavin talking about Area/Code’s wide, GPS-enabled game Crossroads at dConstruct a few years back – and how, once, when testing, it the game’s entirely digital antagonist “Papa Bones” moved through their office, and every GPS-enabled phone they were testing the game on suddenly jumped. What made the virtual “ghost” interesting was when it manifested in the world. Even though it wasn’t real – and everybody knew it wasn’t real – it still made you jump when you were there; the juxtaposition of knowing something is right where you are, even if it isn’t a real thing, is highly striking. I wanted to explore that a little with my own data.

I don’t check up on Mr Armitage In The Past very much. The idea, rather, is that I might bump into him some time. How strange: to be in one of my usual haunts, and know that a ghost of me, a year in the past, is also there, watching a movie, having a drink. Sometimes, those memories are less cheery than others. Sometimes, they’re brilliant. It gives me a visceral memory: reminds my bones, my heart, what they felt. (That, for reference, is my defence against nostalgia. This isn’t just about nostalgia, because you might not like what it makes you feel. It’s just about remembering feelings; stopping to pause and remember the passage of time).

It’s also made me check in to Foursquare a bit more. The moment I fired ghostcar up, I realised I needed to start giving it better data so that it’d continue to have meaning a year in the future. So that’s a strange, interesting takeaway: changing my behaviour because I want the fossil record to be more accurate.

I was only going to find out what it felt like by making it, so I made it. It chugs away on my server in private. I run ghostcars for a few friends, too. It’s not particularly elegant, and I don’t think it’d scale to loads of users, so for now, it’s a private distraction. But I thought I should write it up. If you’d like to run your own install, the code is on Github. It’s a minimally documented Rails app, because it was made just for me, but you might enjoy it.

In the meantime: I go about my business, and an echo of me in the past will do one day, too.