Sony Online Entertainment today announced that more than eight million unique users have registered to play Free Realms, its free-to-play massively-multiplayer online video game (recently nominated for Best New Social/Online Game at the Game Developers Choice Awards). That’s approaching 75% of the World of Warcraft userbase in less than a year, people.

How do they keep it up? New features that prioritize customization and interaction, and freedom to do anything -like cooking, fighting, or just connecting with friends. Parents love it because it’s safe and family-friendly, and kids love it because it’s social networking and gaming at the same time. (I’m sure there are adults that play for their own reasons, as well.)

Later this week, Free Realms is scheduled to kick off the Festival of Hearts, a month-long event that celebrates love, friendship and kindness. There will be themed events, daily social activities, and storyline quests that all stick to the Valentine’s Day theme: hearts, candies, forget-me-not cards, flowers, love potions and more. New Hippo, Tiger, Beetle, Groundhog and Owl pets will also be available in the Marketplace.