The war over virtual building blocks is going into overdrive.

Lego and Warner Bros. Interactive Entertainment have unveiled “Lego Worlds,” a new PC-only game that allows fans to build virtually anything they want using digital Lego building sets.

If that sounds familiar, it’s the basic framework of “Minecraft” — the ultra-successful franchise that Microsoft purchased last September for $2.5 billion.

The game, which is currently available in preview form on the Steam digital distribution service, aims to take the core of the long-running physical building block game and bring it to the virtual world, letting fans both customize pre-fabricated structures or build objects using just their imagination.

“’Lego Worlds’ embodies the physical, Lego brick-building fun that consumers have enjoyed for decades, on a digital platform that delivers an entirely new type of experience with the beloved bricks,” said Tom Stone, managing director of TT Games, which will oversee development of the game.

Lego and Warner Bros. are charging fans $15 for the incomplete game, something that might seem unusual to people unfamiliar with recent trends in the PC gaming world. More and more titles are adopting this method, though, giving fans early access to games — and giving them a voice in the polish and evolution of the titles as they make their way through the development process. (“Minecraft” was one of the forerunners in this style of development.)

The game, at present, doesn’t offer multiplayer functionality or sharing features. And the companies have not yet introduced any of the characters or franchises Lego has previously partnered with (including “Batman,” “Star Wars,” “Lord of the Rings” or “The Lego Movie”). It is unclear at this point whether the game plans to incorporate those at a later date.

The very similar “Minecraft” has been a phenomenon since its introduction. The game has been downloaded more than 100 million times on PC alone since 2009 — and console sales have since topped those on PC. On the Xbox 360, “Minecraft” has sold more than 12 million copies — just 2.5 million short of the total “Halo 3” managed to sell (despite that game’s five-year headstart). Despite its age, “Minecraft” is regularly among the 10 top console sellers each month, according to the NPD Group.