In all honesty your game has to shine, and even then you have to push it with a bit of social marketing.
All of my games have started out with a boost of initial players that came as a result of social marketing.
The best game so far has had continual players since it was released,
and it too started with a burst of players, trickling down to 1 or 2 a day sometimes 10 or 20.
Releasing a major game is like releasing a movie, you make a trailer, build up an audience with that trailer,
then release the game being sure to clearly link to your game on social media.
On that initial release, if marketed well, you'll have a burst of players ready to play it because it is new.
If the game is fun and engaging you'll gain a lasting fan base from some of those initial players.