The short and detailed first-person game was demonstrated in a dilapidated high-rise industrial block that allowed players to avoid tear gas, hide behind burning obstacles and escape the riot police.
Lam, a 30-year-old developer, covered her face and asked not to be named because she participated in a frequent illegal protest. She said: "It allows you to experience the crisis that frontline protesters may encounter."
"It doesn't mean you have to go out after playing the game. We want people who fight for freedom to go out anyway."
Protesters are concerned that Beijing is eroding the freedom that Britain gave when it returned the city to China in 1997 and has been violently communicating with the riot police for the past five months.