It's inevitable that others will follow in the footsteps of popularity. Minecraft has turned into a monster of a game, so it's no surprise that a number of similar titles have popped up recently. But what is it like to live in the blocky shadow of Minecraft? And how does being compared to one of the biggest indie success stories of all time affect the way a game is perceived?

Ars spoke to the developers behind games like FortressCraft and Terraria to find out.

Building a fortress

The frustrations of developers on the Xbox Live Indie Games channel are well documented. One of the few success stories, though, is a game called FortressCraft. Developed by Projector Games, the game allows you to shape the world around you using a variety of materials. It features an enormous world, plenty of freedom, and a blocky visual style.

In short, it's a lot like Minecraft, but on the Xbox 360 instead of PC.

The game is being released on XBLIG in chapters, and the developer has gone so far as to describe the first chapter as "basically Minecraft's creative [mode]" in a post on the Minecraft forums. Despite this, the developers behind the game told Ars that the constant comparisons to Minecraft were a surprise.

"Minecraft creative wasn't the first game to allow running around and building in a voxel world—Infiniminer, Voxlap, plus a dozen others [came first]," said Adam "DJArcas" Sawkins, from Projector Games, "it's simply the biggest, and it's achieved that weird gravitational mass that few other games have."

Sawkins' defense is that, while FortressCraft has much in common with Minecraft—and was initially conceived as a 3D version of Dwarf Fortress—Minecraft itself was also inspired greatly by games like Infiniminer. Essentially, his belief is that the elements that make his game a clone are essential to creating a sandbox-style building game.

"The main example I give is that of a racing game," said Sawkins, who previously worked at both Codemasters and Criterion Games. "All racing games have cars, tracks, tarmac, trees, armco, AI, overtaking, braking, chicanes, and chevrons. To remove any of those things means it's no longer a racing game, apart from maybe trees. If I were to remove voxel rendering, infinitely mutable worlds, perlin generation, or—as one YouTube comment accused me of stealing from Minecraft—grass, then I no longer have a 'Minecraft clone.'

"I also no longer have a game!"

Aside from the way it looks and plays, FortressCraft also has something else in common with Minecraft: it has sold a lot of copies. In its first day of availability, the game sold 16,000 copies and, according to Sawkins, it "has sold better than anything on the XBLIG service to date" with sales approaching the $1 million mark.

Mining in 2D

A game doesn't have to look just like Minecraft to be labeled a clone, though. Terraria doesn't take place in a vast 3D world, but instead in a side-scrolling 2D environment. You mine, you craft, and it's all quite complicated and daunting. These similarities shouldn't be too surprising, though, as the two games share many of the same inspirations.

"The open gameplay and deep nature of games like Dwarf Fortress and Infiniminer was something we really wanted to explore," the development team at Re-Logic told Ars via email.

"We knew there would be some comparisons—both games share the block-based world that first appeared in games like Infiniminer," they added, when asked about the constant comparisons to Minecraft. "We believe it’s a bit of a nonissue, however, as both games are very different. We enjoy Minecraft and [Minecraft creator] Notch has made it clear he enjoys Terraria."

In fact, when Markus "Notch" Persson tweeted about the game early in development, the team says that there was a large spike in interest in the project. When the game was finally released, it moved 50,000 copies in one day, and at its first day peak more than 17,000 people were playing Terraria at the same time. In nine days more than 200,000 copies were sold, with virtually no marketing or promotion.

Notch speaks

Speaking of Persson, as the man responsible for the phenomenon that is Minecraft, we decided to find out what his response is to the games he potentially inspired, and give him the last word.

"I strongly believe that true greatness comes from being influenced by other people's work and improving it, making your own version of it, by mixing and matching your best influences and a few original ideas of your own," Persson told Ars.

"Both FortressCraft and Terraria appear to be inspired by Minecraft, which in turn was inspired by many other games, including Infiniminer, Dwarf Fortress, and Dungeon Keeper. However, I do not believe you can achieve something great or interesting by merely attempting to emulate something successful. It becomes especially embarrassing if you publicly deny any inspiration when it's painfully clear how much of a copy it is.

"Terraria is an amazing game, and if Minecraft is any inspiration for it, I feel proud to be part of its lineage. I play it frequently, and I can't wait to see what the future holds for it. FortressCraft is an obvious attempt to just take something popular and clone it as closely as possible. I still think it's important that people are allowed and able to do things like that, but it's hardly graceful."