Killzone Shadow Fall can handle 24 enemy AIs before “framerate drops,” says Guerrilla
Here’s the second part of my interview with Killzone Shadow Fall‘s lead designer Eric Boltjes (first part here). This focuses on the tech behind the game – building a PS4 engine, what next-gen brings to the action and just how many Helghans Guerilla Games can squeeze on the screen at once.
First of all Boltjes explains how the current Shadow Fall engine has been built from Guerilla’s previous PS3 work: “The engine is still the same,” he says, “But we had to redo a lot of it. It’s a different architecture so a lot had to be re-written”. Interestingly, “a lot of the pipeline for production is still the same”, he points out with the real changes coming from the up-scaling of assets required by the high definition demands of next-gen. “Now it’s x4, x8, because everything has to be higher resolution, has to have more details, more loading, more texture mapping. It’s a lot more work to get the production done in that sense”. Overall he claims, “we had to revamp a lot to go next-gen” but the effort involved was, “a good thing because we just want to make it better”.
“Previously we were limited. You could
have six or seven guys on screen, only two
types, and it had to be at a specific range”
With a new engine and new tech the most “obvious” improvements Boltjes highlights are, “more memory [and] more graphical power on screen”. But better looks aren’t what he considers the most important thing about the move to PS4. “For me as a game designer what I was really interested in was getting more gameplay elements on screen. More enemy types at the same time, more weapon types. Bigger areas. For me that gives us a lot more ingredients to play around with. Previously we were limited. You could have six or seven guys on screen, only two types, and it had to be at a specific range”. The ability to throw more on screen has allowed the lead designer to, “open up much more” and enabled the studio to create the more open ‘gameplay bubbles’ Killzone Shadow Fall is built around.
With the PS4 able to push more enemies on screen I asked Boltjes if there was an upper limit? “Yes. It’s about 24,” he replied, adding “but that’s just enemy AI. And there are other types of enemy AI, lots of destructibility, lots of dynamic objects. Those have much higher limits but the amount of AI is around 24″. That leads to the next obvious question of what happens when Enemy number 25 wanders onto the battlefield. The answer from Boltjes is simple: “framerate drops”. Although he’s at pains to point out that 24 enemies requires an enormous amount of power and something that just wasn’t possible before. “They’re all autonomous, they create their own effects. They’re busy little bees” he says. You’re not just getting 24 Helghans on screen, you’re also getting all their additional effects and interactions, and it’s this that means, “as soon as you push it over  then we get performance issues”.