In a video interview with Geoff Keighley, David Speyrer of Valve, Robin Walker and Dario Casali shared some interesting new details about Half-Life: Alyx. The developers explained why Alyx is a prequel to Half-Life 2, and not the much anticipated Half-Life 3. In addition, they explained why there will be a non-VR version of the game.

As Dario stated, Half-Life: Alyx started out as a virtual reality exploration game and turned into a Half-Life. And even though the team would love to release a non-VR version, that’s not possible at the moment.

We would love to deliver a version of this that you can play with a mouse and keyboard. But, as we said, it started out as an exploration of VR. The more we use the headset, we realize the amount of interactions that this offers, the amount of possibilities that these things give us. The more we explore this, the more we realize that there are so many opportunities that we can’t really translate back to the keyboard.

When you can track your hands separately from your head. They are all 3D space, all following and moving simultaneously, you just can’t do that with mouse and keyboard. And when you put that into the mechanics of the game, the types of interactions that we can do now, we couldn’t do with a mouse and keyboard.

Dario mentioned opening doors as an example of these new VR mechanics. Now, players can open the doors slightly and start firing their weapons, opening them slowly or knocking on them. They can also open them, throw a grenade and then close them.

But why is Half-Life: Alyx a prequel and not a sequel to Half-Life 3? Keighley asked Robin Walker that question, which he said.

I mean, in all honesty, in 2016, when we started this… I mean, Half-Life was just terrifying. Half-Life 3, frighteningly scary prospect, right? And I think that, to some extent, VR was a way of making mistakes, believing that we had a way of doing that.

Because, starting with VR and then trying to think of Half-Life and how it worked and testing them, you’re immediately in a space where we have something we understand well, the main gameplay of Half-Life and a new platform with new perspectives and new possibilities, and we can do that translation, and then watch people play, and within a week or two, we’re starting to learn. We are able to see someone go through this. And it was really easy not to try to think about the general “Oh, we’re doing Half-Life 3” scenario. We could just focus and find out what people like about it and make progress.

And in a way, VR was a little bit, as the machine gun helped us in Half-Life 2. It became the tent post that you can wrap so much around. The innovation around it. And so VR became something that we could get everything involved in. Where Half Life 3, if it’s like “Hey tomorrow you’re working on Half-Life 3!” And you’re like “Oh God!” Terrifying.