Nantes becomes the crime scene in this self-guided detective game, where the clues are hidden in plain sight in the streets around you.

The case is the murder of Balthasar, and the evidence is scattered across the old centre - past Cathédrale Saint-Pierre-et-Saint-Paul, Basilique Saint-Nicolas, Tour Bretagne and Place Graslin. You decode messages, photograph what does not add up and press digital witnesses whose stories never quite line up.

Every puzzle you crack removes a name from the list of suspects. Play as a couple, bring the children along, or send two or three teams out at the same time and turn the investigation into a race - which is what makes this murder mystery game work as well for a team outing as for a day out. The last answer is waiting somewhere in the centre of Nantes.