Sony Online Entertainment's family-friendly PC MMO Free Realms is now up to two million unique registrants, the company announced today.

75 percent of these are under the age of 17, and 46 percent are younger than 13, SOE says, adding that nearly a third of players are female. The company it plans to celebrate the milestone by awarding all its users with a special bundle of in-game items.

The game, which is free-to-play but has optional microtransaction and subscription elements, lets users play, socialize and battle, and interact on a social networking site alongside the game.

It ties into a trading card game playable both with physical cards and inside the game via digital codes. SOE says the virtual cards are "sales leaders" inside the game's digital store.

"In less than a month, Free Realms has captivated a core player base of tween and teen gamers, while also strongly resonating with MMO gamers," says SOE president John Smedley. "We wanted to create a game to play with our families and are excited to have hit the mark with our intended audience."