Procedural Content Generation David Maung, Josh Owusu-Dekyi, Ben Trivett, and Tim McLean

Outline Why PCG? Pros and Cons of Some PCG Methods Dynamic Content Generation Random Content Generation User Mediated Content Generation Some Criticisms of PCG Games With PCG Next Time Questions?

Why PCG? Creates a lot of game content very quickly. Provides replayability through more content. Realistically model things like vegetation and erosion much more accurately and quickly than by hand.

General PCG Methods Dynamic Content Generation Entire game world generated based on algorithm. Only parts around the player are in memory. Random Content Generation Levels are randomly generated at runtime. Used a lot in Rogue-likes. User Mediated Content Levels are generated randomly. The levels are then evaluated and hand edited by developer/player.

Advantages of Dynamic Content Generation Doesn't hog memory for things you can't even see. World is persistent despite being regenerated on the fly. Theoretically possible to have a truly infinite game. Malevolence: The Sword of Ahkranox [2]

Disadvantages of Dynamic Content Generation Constantly uses processor power to generate the map. Usually only used if you want a very large game world. Very difficult to make local changes. Difficult to test that everything is sufficiently interesting. Noctis[3]

Advantages of Random Content Generation Infinite amount of different levels. Most likely will not play the same level more than once. Spelunky

Disadvantages of Random Content Generation Difficult to guarantee that every possible generated level "works". Hard to ensure that there are no boring levels. Difficult to ensure difficulty is consistent between corresponding levels. Spelunky again

Advantages of User Mediated Content Majority of level design work is still done automatically. Lets designers fix issues in the levels before release. Gives levels a sense of purpose. Can spark creativity in level designers. AaaaaAAaaaAAAaaAAAAaAAAAA!!! [4]

Disadvantages of User Mediated Content Content is not infinite, because it is pre-generated. Still relying on some hand editing: Takes more time to generate content. Still need level designers. SSX[5]

Criticisms of PCG Content can seem uninspired. Setting up infrastructure takes time. Law of Diminishing Marginal Utility. Not a real thing.

PCG Game Examples Dwarf Fortress SSX Civilization (series) Minecraft FTL: Faster Than Light Diablo (series) The Elder Scrolls Series

Dwarf Fortress Part roguelike, part city building game released in 2006. Uses mid-point displacement algorithm to create base elevation information. Erodes the terrain with simulation of weather, volcanic activity, temperature models, and other effects. Uses trade simulation to create roads and villages.

Dwarf Fortress Cont.

SSX Continuation of the SSX snowboarding series and released by EA this past February. Mountains and courses were to be initially created solely with PCG. Courses felt mechanical, and not organic/smooth. Used NASA topographic model as a base for mountain creation. Used Houdini to procedurally place hazards and craft mountains into courses.

SSX Cont.

SSX Cont. Avalanches are procedurally generated. Deadly Descent mode creates extra hazards for the player to avoid such as extra trees, rocks, avalanches, thin air, and darkness.

Civilization (series) Maps are procedurally generated based upon constraints specified in scripting language. Modding tools are made available so that players can create their own maps.

Minecraft World was originally generated with 2D Perlin Noise heightmaps. Problems with dull terrain. Switched to 3D Perlin Noise with linear interpolation. World is divided into biomes using Whittaker Diagrams. "Infinite" map are not truely infinite as game becomes buggy at extreme distances,

Minecraft Cont. No win scenarios

FTL: Faster Than Light Space roguelike funded through Kickstarter and released this past September. World is divided into sectors which is further divided into beacons.

FTL Cont. More unwinnable situations Small set of scenarios

Diablo (series) The earlier entries had more procedurally generated towns and dungeons. Diablo III has a hand-crafted hub, and uses larger tiles leading to less variety between runs.

Elder Scrolls (series) The Elder Scrolls II Daggerfell World is procedurally generated at installation. Wilderness, dungeons, quests, and NPCs are as well. Towns and cities are handcrafted for better navigation. Landmass is twice the size of the British Isles. Easy to get lost and difficult to navigate.

Elder Scrolls Cont. The Elder Scrolls V: Skyrim Much more of the game is handcrafted including dungeons. Randomly generated quests are used to pad out the handcrafted ones. Quests are easier to complete as the locations are easier to find. Map is much smaller than Daggerfall's. ~41 sq. km vs ~400,000 sq. km

Next Time Middleware used to help in creation of PCG. Unity Tutorial for generating PCG.

References http://www.lostgarden.com/2007/02/content-is-bad.html http://www.altdevblogaday.com/2012/04/27/the-difficulties-of-an-infinite-video-game-world/ http://en.wikipedia.org/wiki/Noctis http://www.gamasutra.com/view/feature/174311/procedural_content_generation_.php http://aigamedev.com/open/teaser/investing-in-procedural/ http://roguelikedeveloper.blogspot.com/2008/01/death-of-level-designer-procedural.html http://www.sidefx.com/index.php?option=com_content&task=view&id=2211&Itemid=68 http://pcg.wikidot.com/pcg-algorithm:whittaker-diagram http://notch.tumblr.com/post/3746989361/terrain-generation-part-1

Questions?