Happy people can infect other people with happiness and increase the happy energy.
Hopeless people will make surrounding people sad, let happy people infect them as soon as possible, otherwise the happy energy will keep running low. Once the energy runs out, the game is over.
Hopeless people will dispel the happy fog, be careful! Hold the left mouse button can generate a happy fog of the size you choose, which can bring joy and happiness to people that in range.