Last fall, Half-Life 2

Our own Tom Marks recently spent some time chatting with two of Valve’s designers - Animator Jay Benson and veteran Half-Life level designer Dario Casali - to talk about the history of the Half-Life series, why we never saw an Episode 3, and how the groundbreaking ideas Half-Life 2 introduced in 2004 have evolved into the VR prequel launching today.

The biggest lesson, it would seem, is to avoid developing both a game and the engine it’s running on side-by-side. “Half-Life one was completed from start to end, I think, in 18 months. Half-Life 2 was six years,” says Casali, who’s now worked on every Half-Life game since the original in 1998.

“ We threw away a lot of work.

For six years, the team not only iterated on designs for the next chapter of the Half-Life series – which on its own would have taken considerable time and effort – but also completely overhauled the way their games worked, how they were built and, most importantly, how they played.

“We threw away a lot of work,” Casali says. “We were experimenting with the engine, we were figuring how physics would play, and how far we could push the technology. We realized that a lot of the track that we'd made earlier wasn't terribly relevant anymore and we needed to rethink what [that] was going to be as the story evolved and as the mechanics evolved."

Fans of the series might be surprised to learn that for a game that ostensibly revolutionized the use of in-game physics, it wasn’t until almost the last year of development that that aspect of the Source engine was truly put to use. “We realized, ‘Oh, we have this physics engine. We're not really using it to the extent we could," Casali explains. The environmental puzzles, the traps in Ravenholm, even the iconic Gravity Gun were all initially far less important.

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“The initial Gravity Gun prototype,” according to Casali, “Was this thing that you would stick on the object and then you could reel it in using a mouse button and then push it back out using the mouse wheel. So it was this thing that you could just manipulate. It wasn't really a weapon to begin with - it developed into a weapon when we realized the different things we could do around it.”

Of course, the Gravity Gun as it’s remembered today was a much more powerful beast - one that helped fundamentally shift how we think about interacting with digital worlds - and that spirit of innovation was still present throughout the development of Half-Life: Alyx. This time around, though, our techno-manipulators are the Russels, essentially “Gravity Gloves” as opposed to a gun - and much like their still-to-come predecessor, they’re helping reexamine how we interact with objects in VR space.

“ You're a human being doing things, and you do them like a human being would do them.

“The Russels don't cast so wide of a net, [they’re not] this vacuum cleaner, of just, like, ‘bring me physics!’" laughs Benson. “It's like a scalpel as opposed to a cudgel. The Gravity Gun is a very blunt force instrument; it's very direct, even in the way things move to you – you hold down the right mouse button and they kind of just zip straight towards you. The Russels have this balletic elegance to them, where you're creating these graceful arcs, and the fact that you then have to reach out and grab [items] and catch them.”

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These refinements extend throughout all of Alyx’s systems, as well. As we noted in our review, one of the most immersive (and mechanically interesting) aspects of Alyx is that your virtual hands don’t require commands to interact with most objects - you can knock a door shut by simply brushing against it, or use the barrel of your gun to slide open a drawer if you’re scared there’s a headcrab hiding inside (I definitely haven’t opened every single drawer like this).

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Benson notes how, in many games with a lot of interactable objects, we as players end up being “very messy participants,” and how that can create ludonarrative dissonance for the player. Taking inspiration from games like Gone Home and Firewatch (which Benson also worked on before Campo Santo was acquired by Valve), which use a “put-back” system (so your character wasn’t just constantly living in squalor), the Half-Life team wanted to ensure that - no matter how a player opts to interact with the world - the experience feels natural.

“It's a small thing, but that kind of natural design is quite thrilling as someone who spent a decade of their life twisting their brain around how to make interactions feel correct or natural,” Benson explains. “In Half-Life 2, you know that the gun will fire exactly where the reticule is – in Half-Life: Alyx, you've got six degrees of freedom - point [the gun] how you like it. Can you fit the gun through these wooden boards and then over like this? Or can you blind fire around the corner and kill the soldier that way? … You're a human being doing things, and you do them like a human being would do them.”

“The interesting part of developing this just for VR,” Casali explains, “Is that the expectations people have of interactivity and of how things should work is completely different in VR – when you're there and the scale is real, and things feel real to you – than it is on a flat screen where you have this limited keyboard interaction.” This shift in player expectations has resulted in a host of new world-building opportunities for the team, though. Where in a traditional FPS, players might expect to just read the text of a headline on a newspaper lying on the ground, Valve wants to make sure you can pick up that newspaper (complete with floppy paper physics) and read a whole article — if you’re not busy trying to dodge headcrabs. “It's funny how those things just become expectations when people are there,” Casali says. “They get this sense of presence that we've never had before.”

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Of course, this all begs the question: what’s next? It’s probably safe to assume that we won’t be seeing Alyx 2 anytime soon, but both Benson and Casali are excited by the potential of the Source 2 engine. “We run [Half-Life Alyx] at 90Hz in each eye, so you could probably take that and double it,” Casali says, before Benson chimes in, saying, “ Because the fidelity of the game is really, really high, you go ‘Oh, yeah, but we’re having to crush all this into a million billion frames a second with the VR stuff. It’s kind of insane that it actually looks like it does,” he adds with a laugh.

Hopefully it won’t be another decade(+) until we see another Half-Life, but – even if it is – it’s unlikely that Valve is just going to hang their hat back up. While they’ve learned not to develop games and tech simultaneously, Casali says “Hopefully we've turned a corner,” now that they’ve shipped Alyx — though, of course, only time will tell.

JR is a senior editor at IGN and is way more scared of headcrabs now than he ever was in 2004. You can tell him it's all gonna be okay on Twitter if you want.