Make a game that is fun to play. When people comes, they will stay.
☜▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬☜☆☞▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬☞ - Candymaniac, a highly reactive substance.
Just make any kind of game, then go to a popular game that is like your game, and ask those people to help you test it.
Once your game is popular enouph you can just play it and people will join.