How Respawn’s development wizards bend Source Engine to create Apex Legends’ maps

The engine that built Portal wasn't made for battle royale maps, but it's why Apex maps have such a distinct flavor

See those mountains? They aren't just for show. / EA

There’s a spinal column in the middle of Broken Moon, filled with broken bodies, where players are forced to funnel through if they find themselves on the wrong side of a ring closure. It’s infamous among the community as a place where teams go to die, get third-partied, or gate-kept beneath these imposing blue-and-white residential blocks. 

Next season Promenade is going away, its sci-fi skyscrapers replaced by a crater and a quarantine zone with a more open-plan design. For Respawn, though, it’s not as simple as replacing one point of interest with another. 

Look at Apex Legends’ other maps and you’ll notice similar structures separating the larger open spaces. These serve the same purpose as Promenade – solid walls essentially carving the map into distinct pieces, creating mini-battle royale spaces, and keeping everything from devolving into chaos. In King’s Canyon and World’s Edge, it’s the mountains. It’s the phase runner on Olympus. 

Outside of separating the players and keeping matches competitive, there’s a secret art to this that ensures the game’s performance is smooth and consistent. You might not have liked Promenade, but it, and points of interest like it, serve an important purpose. 

Broken Moon's skybox looks way prettier this season / EA

“Maps are designed for performance and limiting draw calls,” design director Evan Nikolich says, referencing the information the game sends to your graphics card to render the visible objects on your screen. Promenade and similar vision blockers keep that information to an acceptable level, which helps the game run smoothly. 

“We have various occluders to make sure we always hit that 60 frames per second on our minimum specs, PS4 and Xbox One, and 30 frames per second on Switch,” he continues. “So we have to create our maps in such a way that we maintain that performance.” 

Although it’s heavily modified, Apex Legends was built on Source Engine. That’s a toolset originally created to power Valve’s games – Half-Life 2 and Portal – which mostly feature linear corridors. Respawn’s tech team has jammed a crowbar into it and bent it all out of shape to support a battle royale game, which is astounding when you consider that live games like this – with constant, game-changing updates – didn’t even exist when Source Engine was created. 

EA

“Getting an engine that was designed for hallways and rooms and building up big open spaces definitely limits us in certain ways,” Nikolich says. “But it also drives us to be very creative in certain ways, and how we design our maps and build unique and fun spaces for combat.” 

EA

When creatives don’t have any constraints, people tend to follow the easiest path forward and go for the most intuitive ideas, whereas creative challenges force people to think of novel ways to solve problems. As a writer, I always found it fun working for print magazines (remember those?) and figuring out how to say what I needed to say within strict word counts. On the flip side, here’s me rambling on. 

“That's the foundation of how we have to build the maps,” lead level designer Steve Young explains. “It provides a great framework for our team. We have to build a map around Struct, which calls out big chunks of the map, players, and everything else. So even though none of this is player-facing, anytime you see a big rock wall or something like that, usually there's something inside there that's occluding everything else behind it. 

“It provides a very deliberate limitation, but it helps. I think when you have these technical restrictions, we're able to work creatively around those to find creative solutions to do some of our best work.” 

The result is a series of distinct, memorable maps that stick in the brain. Regular players can close their eyes and cut a parkour path through some of the most technical routes in Apex Legends. 

EA

There are plenty of battle royale games, but none have maps quite like this, where there’s a clear intention behind every landmark, not only for performance reasons but also for player flow, combat, and how many teams tend to contest each space simultaneously. 

They’re maps where almost every named location, and even the spaces in-between, mesh with legend abilities and player competence to make memorable firefights. Every POI is some past victory or distant trauma you can reminisce about with your squad, and this is a major part of why Apex has such longevity. 

We’ve made it all the way to season 21, but I can imagine myself sitting on my porch as an old man, telling the grandkids about the time I survived a one-vs-three inside one of Apex Legends’ most notorious chokepoints. 

“Back in my day, we had real maps,” I’d say. “There’s no identity in these new-fangled games on your Quantum Box. We used to have frustum culling – it’d only render what you can see! Proper games. Where are my pills, Margaret?” 

“Sure, Grandad,” they’d pat my back. “Let’s get your meds.”