Chris Delay of Introversion Software (the studio behind indie classics Uplink, Darwinia and Defcon) has a different take. Though Fallout 3 is scripted, he feels the game manages to create a sense of freedom with its narrative.
"They did a very convincing job of populating the world. I didn't feel like I was too on rails or anything. It certainly felt much more open than the average first- or third-person shooter," he says.
"So in that sense, they successfully did it. They created a whole world and filled it with interesting stuff. The world never felt to empty or sparse, there was always stuff to do."
Riedl argues that true agency the freedom to change the world and plot isn't actually necessary for gamers.
"I think this is where game designers have excelled: scripting plot lines to create the perception of agency, without actually enabling the player to significantly change the direction or outcome of the game's plotline," he says.
"Players have what I call 'micro-agency', the ability to affect the simulated world from moment to moment, but not the ability to affect the overall plot."
But this approach creates a huge burden on game designers, according to Riedl. "Theoretically, for every branch point the amount of plot-related content that must be authored at least doubles, resulting in an exponential growth of plot-related content."
As the sole coders on their games, this is an issue Steenberg and Delay are only too aware of. "It's very, very expensive to produce all this content its only an option for a really big company," says Delay.
"And of those really big companies, very few choose to go that way, because it's actually much easier and in many ways more reliable just to churn out a Call of Duty: Modern Warfare-style scenario, where generally everything is on rails."
The cost of development means indie developers are frequently more reliant on procedural content that is, content generated by the game itself.
Delay's latest project, Subversion, is a Mission: Impossible-style game in which the player pulls off heists. The game is set in a rich, procedurally generated gameworld that simulates entire cities, including the interior and exterior of buildings, and the security systems that protect them.
"The typical way to make a heist game would be to design some levels and in those levels to script specific things, like this button switches off the security and this guard walks this path and so on," he says.
"But then you get a predictable result and you get predictable gameplay. Rather than coding specific events and set pieces, I've been programming the world to be as general as I can so that security systems genuinely work.
"If you have a camera in a room it doesn't just automatically trigger the alarm it has to be wired into a monitor somewhere, and there has to be a guard watching the monitor and when the guard sees you on the monitor, he has to press the alarm button. And any one of those is a fully simulated system that you can tinker with to your own advantage."
It is this rich simulation of gameworlds which will afford players the option of a wholly dynamic approach to heists. They can approach missions as they choose, and because the world is so deep, numerous options for emergent narrative will exist.
"My initial design idea was to have a gameworld in which there were procedural missions wherever you looked. In any building, anywhere in the city there would be things that you could steal or break into, but that wouldn't be the core game," Delay says.
"My plan is to have this rich gameworld in which the game of Subversion will be set, and the core game will make much more use of hand-crafted levels."
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