Here is a small confession. I have spent an unreasonable amount of my life looking at photographs of roads in places I have never been, trying to work out where they are. The shape of a kerb. The colour of a number plate. Whether the power lines are overhead or buried. It turns out this is a hobby, and it turns out I am not alone in it.

So I built a game.

What it is

Every morning, TripGeoSnaps assembles a fresh set of 50 street-level photographs from 50 different countries. No captions, no labels, no clues beyond what the camera happened to be pointing at. Your job is to work out which country you are looking at.

You play through them five at a time, so a single game takes a couple of minutes. If you have a longer coffee break, keep going — ten games clears the entire day's set, and the game keeps track of how far through you have got. At midnight the whole thing resets with 50 new places.

How a round works

This is the part I am most pleased with. You do not simply get shown a photo and asked to name the country. You get three guesses, and the game gives ground reluctantly.

• First guess: a small circular window onto the image, and eight countries to choose from. Get it right and you score three points.
• Second guess: the window opens wider, and four countries remain. Two points.
• Third guess: the full photograph, and it is down to two countries. One point.

Guess wrong and you watch the options fade away in front of you. That was a deliberate choice. An earlier version quietly swapped in a fresh set of countries at each stage, which was tidier to build and considerably less fun — it meant that ruling something out counted for nothing. Now the list only ever shrinks, so if you have decided this is definitely not Uruguay, that decision stays decided.

Fifteen points is a perfect game. I get fifteen roughly as often as I get eight.

Where the pictures come from

Behind the scenes, the game works through a large database of cities, picks places within them, and asks Google Street View whether anyone has ever photographed that spot. Most of the time the answer is no, which is why building a single day's set involves checking several hundred candidates to find 50 that work.

One rule shapes the whole thing: no country appears twice in a day. It would be easy to fill 50 slots with American suburbs and Japanese side streets, because that is where the coverage is richest. Forcing one country per day means you get Lesotho and Andorra and the Faroe Islands alongside the obvious ones, and it makes the eight-country shortlist genuinely hard.

I also chose to keep the photographs contributed by ordinary people, rather than restricting the game to Google's own camera-car imagery. The car footage is more consistent, better framed and much less interesting. Somebody's handheld panorama of their own street on a bright afternoon tells you far more about a place than a perfectly level shot of a dual carriageway.

The trade is that now and then the game hands you something deeply unhelpful. A wall. Just a wall. But give it a moment and there is usually something to work with — the size and pattern of the brickwork, the colour of the mortar, whether it is bare or rendered, what is growing at the foot of it, how hard the shadows are falling. Sometimes there is genuinely nothing and you simply guess. I find I don't mind that much. Being defeated by an anonymous wall somewhere on Earth is, in its own small way, precisely the experience I was going for.

Go on then

It is free, there is nothing to install, and it takes two minutes. The set changes every day, so if today's Faroe Islands defeated you, tomorrow brings 50 more chances to be confidently wrong about Uruguay.

Play today's TripGeoSnaps

Street View imagery © Google and its contributors.