An online game aimed at helping children see the importance of social distancing during the coronavirus pandemic has racked up about 10,000 plays in its first two days.
Players of Can You Save the World? must keep away from people in a busy street, collect masks and avoid sneezes.
The final score illustrates how many lives have been saved by doing so.
Co-designer Prof Richard Wiseman, said it showed how "just a small amount of avoiding can save lives".
Psychologist Prof Wiseman, from the University of Hertfordshire, said he had been out for a walk during lockdown and thought social distancing "felt like a computer game" as he was "having to avoid joggers and cyclists etc".
Knowing there was "evidence that pro-social video games can change people's behaviour in the real world", he contacted French games designer Martin Jacob.
They created the game in two weeks, a process which would normally take months, with Mr Jacob on the technical side and Prof Wiseman "shaping it psychologically".
"I think it's the first social distancing game and the first Covid game," Prof Wiseman said.
"It encourages everyone to avoid others and secondly makes the point that it does make a difference."
Players of the free game must avoid other people, and collect PPE and healthy food to gain more lives.
"The score increases rapidly, to show that by avoiding one person you are not infecting others and so they are not infecting others," he said.
Prof Wiseman, who has previously talked about how laughter can help people cope during the pandemic, said that because the game dealt with a serious topic it had been "a challenge to create an environment that was fun".
"But it comes back to my thing - getting out a serious message with a sense of levity, it's fun but you're actually learning something as well," he said.
"And you're learning through doing, which is far more memorable than another doom and gloom message."
The game, which is currently only available on computer browsers, is aimed primarily at children but adults really enjoy it as well, he said.
Verity, 10, said it was "really good because it's fun and makes you think about how you should behave when you go out" while an adult player told the BBC he "thought it was realistic in that you have to move for people, they won't get out of your way".