Computer Games, Programming

ProcJam 2014 talks

Last weekend I had the chance to go to the ProcJam talks in London that were part of the ProcJam game jam. Due to some difficulties running errands and never having been to Goldsmith’s before I missed the first talk and arrived halfway through the second.

I was hoping for some tech-focussed talks about coding up procedural generation. As it turned out it wasn’t quite that kind of event but it was still pretty interesting.

Tanya Short’s talk about some of the theory behind procedural generation was quite interesting (despite a flaky Google Hangout connection). The key takeaway from her talk was to look at the structure of what you are creating. Creating believable content means creating a simulation of the creation itself while making it satisfying to explore means adding an emotional dimension.

An example she gave was of name generation, you can totally do the Elite random syllable process but to create more believable names you can introduce structure, like lineage, nicknames and titles appropriate to the society and social ranking of the character. Introduce aspects of the way that people name their children in the real world: things like fashionable names and trends that apply to characters of a certain age, repeated usage of names within families, the use of names to honour significant people in the parent’s lives. These things add emotional depth.

Tanya is working on the game Moon Hunters and she mentioned an example from the game of how personalities consisted of the following factors:

  • the results of the character’s deeds
  • the perception of others
  • how the characters contrast to the villains
  • the needs of the story and plot

I was particularly struck by the idea that the way a character behaves is bound by how they think other people expect them to behave. That’s something we see a lot in the real world and creates exactly the right emotional connection in someone who is trapped between their “true” and “public” selves.

The talk I most enjoyed was by Hazel McKendrick who is one of the developers on No Man’s Sky. For someone who doesn’t really do game programming or procedural generation it was a helpful introduction to some of the basics.

First of all she made it clear that procedural generation isn’t about randomness, abrupt jumps in the underlying numbers creates a jarring inconsistent experience for the player. In mathematical terms we don’t want to use truly random generation but instead functions that generate continuous (smooth) results. This means using noise functions rather than pseudo-random algorithms. Most people mentioned Perlin noise but Hazel also mentioned Perlin worms and Whorley noise.

She also made the great point that games are made by their special moments and rare events in the game. If the generator creates content uniformly then the world is overwhelming and might actually become boring as repetition robs the feeling of being special.

In No Man’s Sky they want the bulk of worlds to be fairly unexciting and plain and allow the player to control their experience by having the more alien or extreme worlds be at the periphery and key game world experiences at the core of the galaxy. The player determines what kind of experience they have by the depth of the region they choose to explore.

Objects in the world matter more when they exist in relationships to one another. Hazel used the example of trees, undergrowth and bushes but it also fits in with Tanya’s talk in that people are more interesting if they exist within societies, lineages and families.

Therefore the generators need to be aware of the context around them and simplest way to do that is to nest the generators so that a generator creates a set of consistent generators that then generate sympathetic output. These generators can nest to any depth and are testable as units and as chains, something that I agree with from my experience with using functional programming although Hazel is working in C++ in a slightly more conventional programming situation.

When nesting generators these way you need to check very large datasets to see that the results truly are consistent rather than frequently consistent. You can program limits on the generator to bound their output but part of the point of using procedural generation is to create things you weren’t expecting. In her slides Hazel had some examples like spaceships where it was possible to generate large catalogues of spaceships to browse visually for anomalies.

You can also write test suites to search for situations that are out of bounds and again from a functional perspective I could see the value of generative testing to exhaustively examine output to find issues with particular inputs identified as the problem.

In a question after the talk Hazel also mentioned that generators are always consistent and finite and that changes to the player’s world are held in state outside of the generators. No Man’s Sky is a mingleplayer game where players will be able to play in the same universe and share discoveries but don’t necessarily have to be in sync to play the game or impacted by the other players activities. You can explore the game at your own pace.

Hazel’s talk is on YouTube

The other interesting talk was by Mark Johnson who is working on Ultima Ratio Regum which will one day be a rogue-like exploration game about empires and the evolution of societies but at the moment is an insanely detailed world-building program that creates a world, nations within that world, their history, cities and human terrain.

At one point in the talk Mark demonstrated how it was possible to zoom into a terrain square in the world and look at the leaves in the tree.

In terms of generation Mark’s talk was similar to Hazel’s but he used the metaphor of card decks. You shuffle cards and draw and the selected card opens new card decks that can be used for choices at a more detailed level.

His example was selected the leadership model of a nation and then its economic and foreign policy. So if you select Isolationist as the foreign policy you don’t want to have Free Trade as the economic policy. Similarly religious freedom should not be available if an earlier choice was theocracy.

This cascade set of consequences even extends to where the religious buildings are placed in cities. A populist religion mean that religious buildings are scattered throughout the city, a state religion concentrates them in the governmental quarter.

Mark’s analogue metaphor was interesting and more accessible perhaps, as long as you get the card decks nested within card decks idea. He mentioned that he thought board games were the most exciting realm of game design as you can experiment relatively cheaply but as the players run the game you must be capable of expressing the rules extremely clearly so they can be understood.

One nice detail was that the game produces books about the history of nations and people within the nation. This will ultimately be how a player discovers things in the game beyond literal exploration and conversation with characters. He illustrated this by showing how he could locate the grave of a historical character from the information in that character’s biography.

While its an achievement to have a game that has that level of internal consistency at some point he does also want to allow for alternative narratives where, say, a character involved in a war between two nations would be mentioned by the histories of both but with perhaps very different perspectives on that character’s behaviour.

Mark Johnson’s talk

I’d like to complement the organisers of the talk for putting together a pretty interesting programme.


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