Like World of Warcraft or Disney's Club Penguin, Lego Universe, which is to be released in the second half of the year, is a Massively Multiplayer Online game, or MMO which can incorporate thousands of players at once.
"Think World of Warcraft, Second Life and Club Penguin all wrapped into one," said lead producer Chris Sherland of NetDevil, the development company behind Lego Universe.
"The back story is basically that there's this evil force that has corrupted the purest source of imagination in the universe," he said.
"Everybody in Lego Universe gets their own planet, their own shard of the universe, and they're sort of banding together to try to defeat that force.
"You do that through this adventure game that's basically quest-based."
Lego Universe will also allow players to make their own game to play on their own planet, and then invite friends come to the planet and play together.
"You get bricks as loot," Sherland said. "You take those bricks and build anything you want. Anything you can build in real life you can build inside Lego Universe."
Anything created in Lego Universe can also be ordered online from Lego.com.