“Minecraft,” created by Markus Persson four years ago, has become one of the world’s most popular video games. Its 22 million users make it three times more popular than “World of Warcraft.” The virtual world’s simple gameplay provides users with creative freedom, offering Lego-like blocks to build basic structures that can be later transformed into palaces. It is also giving other game developers the idea that a successful video game can be made independently.

The cross device and cross platform sandbox game was initially released without investors or publishers, and serves as an example for other indie game makers. “Minecraft” earned $86 million in profits in 2012.

The game takes a simple approach, written in Java to emphasize speed and agility, rather than wider capabilities. This continues in its gameplay by using simple blocks to build a world instead of attempting realism with “mining” in order to “craft,” or determine the material of blocks and what will be built.

The strength of the game is giving players freedom to create what they wish. “There are almost no goals or commandments to guide or moderate behavior, apart from those of the players’ own making,” notes MIT Technology Review. “Its intelligent design reveals a watchmaker’s precision, while the elemental freedom it offers its inhabitants taps into some primal, irresistible human urges.”

“Minecraft” does have antagonists, skeletons and zombies to avoid at night while one builds during the day. And as players build, their constructions become more complex and more detailed — a hut becomes a shed, to a house, then to an estate, and then a castle, each with more features.

The social connectivity is a major feature of “Minecraft,” where users can post YouTube videos of their creations or exchange design ideas. Players can also visit and tour each other’s worlds, as well as collaborate on building projects.

“Minecraft” is motivating players to build their own games, whether by formal schooling or using Gamemaker development tools. The game is available on PC, Mac, Xbox 360, iOS and Android.