There's a group of game developers out there who've committed themselves to making interesting games using voxel technology. In February, we explored how some developers like the makers of Fugl are making beautiful-looking games using the blocky aesthetic. But after that story Tuxedo Labs took Steam by storm with the Early Access title Teardown.

While some of the other voxel-based games that have gained a lot of attention have focused on beautiful aesthetics and majestic worlds (or even the building blocks of Minecraft), Teardown goes the opposite direction: it's a game about destruction, wrecking beautiful voxel creations in a chain-reaction effect to pilfer the vaults of ne'er-do-well business folk and get away before the cops roll up.

Why is ripping buildings apart in Teardown so much fun? How did a small team manage to take this game to such a polished Early Access release? What's the relationship between Teardown's technology and its heist-y game mechanics? These are some of the questions that Teardown co-creator Dennis Gustafsson discussed on the GDC Twitch Channel a few weeks ago.

Instruments of destruction

When you look closely at Teardown you can begin to understand how its environmental destruction mechanics differ from a lot of other games that have elaborate destruction mechanics. In many games that tout destructive technology, it's often something of a very well-polished side effect; a flourish on the player's experience rather than the central goal.

In large games, destructible terrain can look like the explosive environments of the Battlefield series, or players neatly chipping away at walls to build other combat lanes in Tom Clancy's Rainbow Six Siege. But in both games, the environment is reacting to a core gameplay loop not that different from similar games like Call of Duty or Counter-Strike.

Teardown's destruction takes that side effect and puts it center stage, and voxel tech was what made it possible. "I have a history of making destruction-based games," Gustaffson explained, referring to titles like Smash Hit. He found voxel technology to be far easier to use in destruction mechanics than polygons were, because "they're so much easier to work with" when implementing destructive physics.

Early prototypes for Teardown looked a lot like the current game--it was a sandbox where players could just tear apart buildings to their heart's desire. But Gustafsson said it was difficult to build a central game mechanic in this environment because any traditional game objective could just be solved by the player creating a straight line from A to B, destroying everything in their path.

"You can't restrict the player with walls and doors," he said. "It was a long process to get to this type of game."

So if restricting players was impossible, why not make overcoming those restrictions the objective? Teardown's a hest game, but it's also a "beat the clock" type game. Once players grab the first item they're supposed to steal in most of the game's missions, they have a limited time to grab the rest of the loot scattered throughout the map before they're caught.

But even when the model of "plan and do a heist" was added, the right play structure wasn't immediately evident to players. "We had a puzzle [prototype] that was also a heist game, but the difficulty came more from getting to the goods and not planning an optimal escape route," he said.

"But for that to work, you had to have very limited amount of resources like two bombs, four shells in the shotgun and the game just doesn't become fun with all these limitations. I think a way to get around that was to pretty quickly ramp up the resources and hand out new tools pretty aggressively to the player."

Because of Teardown's open-ended objectives, players have a different relationship with the space of its levels that Gustaffson says has meant he's "never seen the same level completed the same way twice." Level objectives are nested behind different kinds of walls, some will crumble if you so much as glance at them, while others might require running a dump truck through a metal wall to gain access.

One player defied Gustafsson's expectations by paying attention to the various power lines running through the levels. In one level called "insurance fraud," the player is tasked with moving seven cars onto a truck before the timer runs out. Most players find ways to drag the cars using tow trucks or other objects to the truck. "He built a slingshot out of these electrical wires," Gustafsson explained. "He [tauted] them up with a huge excavator to build tension connected with a wooden plank, and then set fire to the plank like a fuse."

"And when that snapped off, the wires can slingshot the whole vehicle into the transport truck."

It's worth noting that Teardown, with a hefty campaign and free-running sandbox mode, is still only in Early Access, with more features to come as Tuxedo Labs finishes development. Gustafsson said this was Tuxedo Labs' first game on Steam, boosted by a decent amount of viral clout they'd gained on Twitter thanks to early videos of Teardown.

But even with that clout, Gustaffson said launching Early Access was still an act about "setting expectations," he said. "We didn't really want to launch and till we could show our vision with the game."

"I think that's where Early Access can go wrong. If you show something and then players find out that this wasn't really the way we wanted to make stuff, and try to change in response to that that you're going to disappoint at least 50 percent of the people buying your game."

What powers Teardown's voxels

Now for the tech-inclined folks, we've got some useful details for you. During Gustafsson's conversation with us, lots of viewers were interested in the particulars of the voxel technology that makes Teardown function.

At the core of Teardown is a custom voxel engine that, unusually, doesn't align its voxels on straight lines using axis alignment. "Instead of one big volume of billions of voxels, I have thousands of smaller volumes that are filled with voxels," he said. "Everything is straight within its own volume, but I have a lot of them instead."

For collision, Gustafsson said that Teardown uses voxel versus voxel powered on the CPU, while rendering takes place on the GPU. "There are no triangles in this game," he said with a laugh. "Everything is volumetric data, except for water surfaces and the power lines."

Teardown's also gained some attention for being one of the few games that can run extremely gorgeous ray-tracing technology on lower-end devices. (Gustafsson said the lowest he recommends running the game on is an NVIDIA 1070, but we had it running fine on a slightly older 970). The game uses SSR for reflection color, instead of full-path tracing mainly "for performance reasons."

"Since everything is voxels, ray-tracing becomes much cheaper," he said. "I actually have a separate voxel structure just with the 3D occlusion data so to speak. Where I perform the ray tracing, that also means I don't have access to any colors in that data structure."

To handle primary rays, Teardown starts by rasterizing a bounding box for each object, then marches the visual grid of that object in the shader. "As I said before, there are thousands of these individual volumes, a safe being dragged is one volume all the little debris on the wall it hits is also an individual volume."

"And for each such volume, it's just rasterized, a bounding box and then raymarched in a fragment shader to see which voxel you hit. And then there's a material lookup of indexed pallettes for each object."

Teardown's still got a ways to go through Early Access, but it's already a neat, technically-fascinating gem to emerge out of 2020.