‘Functional, in the main. You’d need to attract them from the general population and inspire them to walk away from their lives in order to play.’

Mark wrinkled his nose, a sign that he was deliberating. ‘Why are you asking, Augusta?’

‘It’s just a project. Theoretical in the main.’

‘And it has to be a game, does it?’

‘As opposed to?’

‘A simple incentive or bet.’

‘Like a dare?’

‘Psychopaths tend to be attracted to high-risk activities with high potential gains,’ said Professor Layton. ‘Think about studies into psychopaths and gambling. They live in the moment, so they treat each bet as an isolated event. Non-psychopaths might start out with a nothing-to-lose attitude, but once we’ve won or lost a few rounds we become protective and cautious. Our past experience affects our future decisions. But psychopaths simply carry on betting high as if every round is the first. It’s a good strategy, too; they win more often.’

‘The risk is high – leaving their lives and so on – so there needs to be some truly impressive gain too?’

Mark nodded. He looked out of the cafe window. It had started to rain and passers-by were putting up umbrellas and hoods, or sheltering under newspapers held above their heads. ‘Or perhaps you’d need a series of continual wins. Just like gambling. Psychopaths need more and more stimulation to experience that feel-good factor, which is why they go to such extremes, but an on-going stream of quick wins would work just as well as one larger deferred win. Better in most cases, I’d expect.’

‘Like Scientologists and their levels of initiation. Their followers are always hungry for more because they’re constantly working towards the next level of membership.’ Bloom was finally getting some traction on what such a game might look like.

‘And like all the best video games.’ Layton stacked his coffee cup and saucer on top of his plate and placed his knife and fork next to them.

‘I was also thinking that to select such people in the first place you would plant profiling questionnaires on social media,’ Bloom said.

Layton wrinkled his nose again. ‘Well, that would give you a sample of psychopaths who like to engage in social media. But I expect you’d need more data for a psychopathic diagnosis.’

‘Exactly. You would use their whole online profile.’

‘People reveal too much online. And if they’re on Facebook and Twitter, we get two sides of their personality. Facebook reveals their idealized self – “me as I wish the world to see me”.’

‘The facade?’

‘Indeed,’ said Layton. ‘And then Twitter provides a more anonymous forum where they can express their truth, whether it be anger, bitterness, prejudice or joy.’

‘The private self.’

‘It would be tricky to avoid attracting non-psychopaths. A lot of people have dark inner lives for all sorts of other reasons.’

‘The abused, the angry or the downtrodden might all exhibit similar profiles.’