Montreal International Game Summit 2016

Montreal, Video Games

Uncharted 4 AI Debug

On November 15th, I’ll be speaking about combat design and AI in Uncharted 4 at the Montreal International Game Summit. My talk explores how we navigated the extremes of combat design philosophy (tightly authored vs fully systems-driven) throughout Uncharted 4‘s development, and how we found our best results with a hybrid approach.

Ahead of my talk, I did a short interview with Brendan Sinclair at GamesIndustry. We discussed a number of topics related to AI design, including why our early attempt at a simple point-to-point search behaviour failed:

“In another instance, they used some pathfinding AI from The Last of Us to get enemies from point A to point B. Gallant said it was soon clear that the AI worked especially well in The Last of Us because the game’s tight, complex environments ensured that the enemies would traverse environments in mostly human ways, using aisles and doorways, walking around desks and other obstacles in the layout. But in Uncharted 4‘s larger, more open layouts, moving from point A to point B usually meant travelling in a perfectly straight line, which wasn’t terribly interesting.”

“The solution was to run paths throughout the layout that AI would move along, trails that would have them reasonably making their way throughout the level, perhaps clearing out corners or other places the player could be hiding on the way to their destination.”

Attending MIGS this year is also a nice homecoming for me. Not only was I born and raised in Montreal, I was actually a student volunteer at MIGS way back in 2009. It’s a real honour to be able to come back as a speaker seven years later.

You can catch my talk at 3:45 PM in room 519A on Tuesday November 15th. If you’re attending MIGS, I hope you’ll swing by to say hello!

Disclosure: As a speaker, MIGS is covering my flight & accommodation during the conference.

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A Taxonomy of Randomness in Hearthstone

Video Games

Hearthstone: Whispers of the Old Gods

“RNG gets your emotions really high and really low. It makes you really feel. Sometimes when I play a game I’m just going through the motions and I’m not getting those highs and lows, but in Hearthstone I get them all the time. It makes me want to come back and play more.”

Mike Donais, Hearthstone senior designer

Randomness is a perpetual topic of conversation among Hearthstone players. It’s generally accepted that a game with random elements can be highly skillful and competitive. However, each new expansion revives fears that Blizzard may have tipped the balance too strongly towards luck at the expense of high-level play. The evolution of the game has been particularly visible this year, as Blizzard phased out two of Hearthstone’s older expansions to create a new standard set for competitive play.

RNG is often treated as a monolithic quality, but Hearthstone actually employs many distinct types of randomness in its mechanics. Some cards allow players to influence their odds by modifying the board state. Other cards use randomness as a strength, providing situational versatility. Some cards become more reliable with careful deck construction, and others vary based on the opponent.

Fundamentally, randomness is created by picking randomly from a set. For example, a coin flip picks from the set of {heads, tails}. While each card interacts with randomness in a unique way, they can be broadly categorized by the set that they randomly pick from. In other words, the set of possible outcomes defines a type of randomness. We can use these categories to chart the evolution of randomness in Hearthstone through the years.

To begin, I need to limit the scope of my inquiry. Because Hearthstone is played with a shuffled deck, there is an inherent randomness in drawing a card. It could therefore be argued that Blackwing Corruptor (“if you’re holding a Dragon, deal 3 damage”) has an element of luck to it. For the sake of brevity, I will only be considering cards where a player with knowledge of the visible board state could not predict a card’s outcome in every situation.

Bluffing and hidden information are also outside the scope of this discussion. All of the “secret” cards in Hearthstone are triggered off of deterministic conditions, and are therefore not inherently chance-based. However, some secrets do have some randomness in their triggered effect.

COIN FLIP

Type - Coin Flip

A 50/50 coin flip is the most fundamental random game mechanic. Hearthstone employs it only sparingly, mostly as thematic flavour for clumsy ogres. Interestingly, pre-nerf Nat Pagle triggered at the end of turn, guaranteeing at least once chance for a card draw. This reliability made him a popular inclusion during the public beta, until he was adjusted.

RANDOM TARGET

Type - Random Target

Randomly choosing from the set of characters on the board is the most common type of randomness in Hearthstone. These cards should theoretically be more random than a coin flip, since “a random enemy” selects from an upper bound of 8 targets. In practice, these cards reward skillful play because players can modify the board state to favour their desired result; they’re more unreliable than they are truly random.

Deadly Shot destroys a random enemy minion, which in the worst case has a 1 in 7 chance of hitting the desired target. However, if the other minions can be cleared from the board, then the spell will have a single deterministic target. Cards that restrict their target selection by some characteristic (“Murloc” type or “with 2 or less attack”) further reduce the set of targets, providing players with even more control over the outcome.

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The Mystic Western Game Jam

Programming, Video Games

El Viaje Misterioso

Austin’s independent games collective Juegos Rancheros hosted another game jam this summer, and this year the theme was “mystic western”.

I hadn’t initially planned on participating, since I was already rather busy preparing for some summertime travelling. However, I was struck with a fun game idea that really fit the theme and scope. I wanted to make a game based on a specific scene from a 1997 episode of The Simpsons, where Homer hallucinates a mysterious voyage through a desert landscape under the influence of extremely spicy chili peppers.

For the gameplay, I took inspiration from the indie platformer Knytt Stories by Nifflas. It has a very clean, blocky, simple aesthetic that seemed feasible to imitate, even with my limited art skills. I also wanted to emulate its low-key pacing and its focus on exploration over combat. Having enemies to fight wouldn’t fit the vibe of the source material, where the mystic desert was mysterious but not threatening. Ultimately, I managed to translate almost every beat of the five minute hallucination sequence into some sort of playable experience (with the notable exception of the snake, which sadly was cut for scope.)

Mystic Western Jam - Notebook Sketches

Developing a platformer was also a good excuse to apply some of the lessons I learned from Steve Swink’s “Game Feel”. The book breaks down and analyzes the ways in which designers manipulate game physics in unrealistic ways to make platformers feel good. For instance, it taught me to increase gravity when the player is descending to avoid feeling floaty. I also implemented variable jump height, input buffering, and late jumping based on the lessons from this book.

You can download El Viaje Misterioso for Windows and OSX here:

Download from itch.io

Download (Windows)

Download (Mac OSX)

Source Code (GitHub)

At the end of the game jam, I was very proud to find out that my entry was one of the 25 games selected for the Mysteric Western Arcade at the Marfa Film Festival. I sadly couldn’t make it out for the event, but I hope people got a chance to play it there!

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Yharnam Metal Hypernym

Internet, Programming

To start off 2016, I thought I’d take a moment to write about some of the new Twitter bots I assembled last year. In my last post on the subject, I indicated that I was reluctant to continue making bots because it was distracting me from larger projects. However, since lately I’ve been focusing hard on a big exciting endeavour, I’ve found that making bots has continued to be a relaxing creative outlet in my downtime.

Yharnam Notes is a small tribute to Bloodborne, one of my favourite games of 2015. The game’s asynchronous multiplayer features include the ability to leave notes for other players using templates of words and phrases. These permutations can often be inadvertently lyrical, as Natalie Zed explored in her Bloodborne poetry. Inspired by this, I made a bot that constructs random messages using the vocabulary of the game’s note system.

Hypernym Bot was inspired by the folk proverb “For Want of a Nail”. I wanted to find a way to generate the same structure of text programmatically. Fortunately, Wordnik maintains a list of hypernyms (words that are more generic or abstract) for each word in their database. This made it simple to start with a random word, then iterate up the chain of abstraction of few times.

This is one of the silliest ideas that I’ve actually followed through on. Somehow my errant thoughts on @EveryWord and heavy metal clichés intersected, and led me to render every word in the English language in a heavy metal font. Tweeting a new word every four hours, @EveryMetalWord will complete its task by 2065.

You can find the complete list of my Twitter bots here. Wishing you all a happy new year, may your 2016 be programmatic and random!

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Challenges for Game Designers

Books, Video Games

Challenges for Game Designers

For the last few months I’ve enjoyed following along with Liz England’s Game Design Book Club. Though I’ve only been participating intermittently, it’s been really valuable as motivation to read books that are often cited and highly praised in game development circles. It has also pushed me to explore certain topics that I may not have chosen on my own.

September’s book club selection was Challenges for Game Designers by Brenda Romero and Ian Schreiber. It covers some common ground with other “game design 101” books aimed at a classroom environment, but it has two unique twists. Firstly, it has an emphasis on non-digital games. This affords a greater focus on “pure” mechanical considerations: chance, skill, strategy, social dynamics, etc. Secondly, as the title suggests, the reader is encouraged to explore the topic of each chapter by completing assorted design exercises; it’s equal parts textbook and workbook.

I was very impressed by the variety of exercises presented in the book. The ones that particularly interested me (and, admittedly, took the least time to complete) involved taking an existing game and modifying it to emphasize a different type of skill.

For instance, one of the exercises in chapter 5 was to “modify [Tic-Tac-Toe] by adding one or more chance-based mechanics”; the game should also be “good for adult players”. I thought this challenge was quite interesting, so I took some time to develop a small game called Catalina Tiles for it. The game is played on a nested 3×3 grid, and players use four 4-sided dice to determine which tiles they can claim on their turn.

Rules for Catalina Tiles [PDF]

Another exercise in chapter 8 involved choosing a “non-digital game with no elements of chance at all” to modify by adding fog of war: “your opponent’s pieces are hidden from you (and vice versa) except under certain conditions.” After researching existing chess variants (there are so many), I developed two unique hidden-information chess games. Luft Chess is standard chess played with invisible kings, and Reverse Schrödinger’s Chess has each player secretly deploying their opponent’s back row pieces.

Rules for “Fog of War” chess variants [PDF]

I had a lot of fun completing these exercises (also learning how to use LaTeX to make fancy rulebooks). Even as someone who works on games every day, it’s been valuable to stretch my creative muscles and make games under unfamiliar constraints.

The Game Design Book Club is online and open to everyone, so feel free to follow along if it interests you. The November selection is Shooter, “an anthology of critical essays about first-person shooters” that Clint Hocking has spoken highly of.

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