GDC talks folded in: AI, design, math and feel

Fifteen talks whose lessons were small enough to fold into existing skills as a few lines each, plus one small tested addition (shuffle bags and pity timers). Speaker names are as transcribed by Whisper; doubtful spellings are flagged. Years are only given when the talk states or clearly implies them, and say which. The lessons are summarised in our own words; read the talks for the full argument.

AI

AI Arborist: Proper Cultivation and Care for Your Behavior Trees

• Speakers: Mika Vehkala (Whisper: "Vehkela"; Remedy), "Bobby" (surname not in the transcript), Ben Weber. Year not stated.
• Video: https://www.youtube.com/watch?v=Qq_xX1JCreI
• Taken: trees execute a decided behaviour while a state machine above them handles cycles; the "how many places to delete a behaviour" test; retry after failure with a timestamp and a condition (10 s in the example); avoid uninterruptible nodes. .agents/skills/game-ai/SKILL.md section 2 (summary) and pitfalls.md.
• Not taken: tag and breakpoint decorators, run-time subtrees from smart objects and Weber's StarCraft managers. They need a tree editor or an engine the kit does not ship.

Nuts and Bolts: Modular AI From the Ground Up

• Speakers: Christopher Dragert (Whisper: "Draggart"; Ubisoft Toronto), Kevin Dill (Lockheed Martin), Troy Humphreys (Turtle Rock). Year not stated.
• Video: https://www.youtube.com/watch?v=IvK0ZlNoxjw
• Taken: roll a random cooldown once per action, not per tick (Dill's sniper; a 60-tick simulation for the kit: 61.3 s average re-rolled against 89.8 s rolled once, 1,000 shots); actions do not change world state as a side effect; sensors with a maximum stale time per character type on a budget (Humphreys, Evolve). pitfalls.md, perception.md.
• Not taken: the blackboard/whiteboard split and interface checks on blackboard keys, which presuppose a data-driven module system the kit's plain C# classes do not need.

Knowledge is Power: An Overview of Knowledge Representation in Game AI

• Speakers: Daniel Brewer (Warframe), Rez Graham. Year not stated.
• Video: https://www.youtube.com/watch?v=Z6oZnDIgio4
• Taken: the target record's extra fields (which sense, first- or second-hand, reachable) and caching "unreachable" until the target moves, tied to the skill's existing short-path signal. perception.md.
• Not taken: terrain as a bit mask for combinable costs (Godot's navigation costs are per region, not per query, so the mapping would need its own test); influence maps, intensity and Sims-style long-term memory (survey material).

The Simplest AI Trick in the Book

• Speakers: Steve Rabin; Jonathan Adamczewski (Whisper: "Adamchefsky"; Insomniac); Rez Graham (Whisper: "Reg Graham"); others not taken. Year: about 2015, inferred (announced as the day before "AI Disaster Stories", below).
• Video: https://www.youtube.com/watch?v=iVBCBcEANBc
• Taken: human reaction times for enemies (0.2 s simple, 0.15 s to sound, 0.4 s friend-or-foe); disconnected navmesh islands waste searches and trap enemies, and Insomniac removed about a quarter of Sunset Overdrive's triangles by flood fill. perception.md, pitfalls.md.
• Not taken: the C++ enum-to-string macro, the blackboard store and Warframe's learned wall-run links.

Winding Road Ahead: Designing Utility AI with Curvature

• Speaker: not named in the transcript (Curvature's author, at ArenaNet). Year not stated.
• Video: https://www.youtube.com/watch?v=TCf1GdRrerw
• Taken: log each consideration's raw input, normalised input and curve output per target, and a "stalled" event when nothing scores. pitfalls.md (linked from SKILL.md section 2).
• Not taken: the tool's UI (input ranges, curve presets, shared inputs). A sandbox tool is out of scope.

Mind Your Step: Avoiding 3 Common Pitfalls in AI Development

• Speaker: Jan Muller (perhaps "Müller"; Insomniac). Year: about 2016, inferred (Ratchet & Clank for PS4 "next month").
• Video: https://www.youtube.com/watch?v=ZlShFdoAOxU
• Taken: one role per companion (teacher, VIP, soldier), metering what companions give, and escalating a fight rather than only removing weak points. .agents/skills/game-design/SKILL.md section 5 (summary) and pacing.md.
• Not taken: enemy variety judged by player mechanics and the memory research, already close to the skill's MDA advice.

Tales from the Trenches: AI Disaster Stories

• Speakers: Steve Rabin (first up), a Sony basketball AI lead (not named), Mark Singer (Red Storm), Rez Graham (Maxis), others. Year: about 2015, inferred ("17 years later" after a 1998 talk).
• Video: https://www.youtube.com/watch?v=__5whYgSTV0
• Taken: disabled branches must be loud (one shipped, about 75% of a designer's year); traits must not skip availability tests (The Sims Medieval's executioner); show what the AI is doing (ShadowWatch's flanks taken for teleports). pitfalls.md.
• Not taken: 2D placeholders, root motion, gesture clips and offensive object names: anecdotes without a rule for a Godot game.

Design

Open-Ended Puzzle Design at Zachtronics

• Speakers: Zach Barth ("I'm Zach"), with Drew Messinger-Michaels (Whisper: "Messenger Michaels"). Year: probably 2019, inferred (Exapunks is the latest game); not stated.
• Video: https://www.youtube.com/watch?v=U4uH1ynH3Rs
• Taken: bounce per puzzle; solved-but-too-hard counts as too hard; care for the first puzzles; the last is not the hardest; a working example beside an empty puzzle; easier rules over harder teaching; no real-time simulations; cut constraints that add no intended difficulty; depth in optional optimisation. game-design section 6 (summary), .agents/skills/game-design/pacing.md, and the level_opened/level_solved line in .agents/skills/game-telemetry/SKILL.md.
• Not taken: the paper worksheets on a wall (a studio habit, not a rule an agent can apply).

Ten Principles for Good Level Design

• Speaker: Dan Taylor (Square Enix Montreal). Year: probably 2013, inferred (the Journey talk "yesterday"); not stated.
• Video: https://www.youtube.com/watch?v=iNEe3KhMvXM
• Taken: introduce, showcase or subvert a mechanic per level; what to do, not how; an easy-to-medium main path with signposted risk and reward; greybox risky ideas early; a way back that plays differently; design from the emotion. game-design section 7 (summary) and pacing.md.
• Not taken: the remaining principles (surprise, empowerment, aesthetics), already covered by the skill's MDA section.

Cursed Problems in Game Design

• Speaker: Alex Jaffe (Riot Games). Year: 2019, inferred from his joke about "loot table distributions for 2019".
• Video: https://www.youtube.com/watch?v=8uE6-vIi1rQ
• Taken: the test (could tuning or content remove it? then it is only hard) and the four responses, each naming what is given up, written into an ADR. game-design, "In a review", step 5.
• Not taken: the worked examples (politics, auction houses, quantified creativity); the ADR template is unchanged.

Math and feel

Math for Game Programmers: Fast and Funky 1D Nonlinear Transformations

• Speaker: not named in the transcript (he refers to his own earlier curves talk). Year not stated.
• Video: https://www.youtube.com/watch?v=mr5xkf6zSzk
• Taken: ease the parameter t; smooth start and smooth stop ("flip, power, flip"); the crossfade that is smoothstep; blends instead of Pow; arches. .agents/skills/math/SKILL.md, "Easing".
• Measured on Godot 4.7.2 headless: Tween.InterpolateValue with Quad/Cubic/Quart/Quint and EaseType.In gives t², t³, t⁴, t⁵ (0.25, 0.125, 0.0625, 0.03125 at t = 0.5), Out gives 1 - (1 - t)², ease(t, 2) = t², ease(t, 0.5) = 1 - (1 - t)², and smoothstep(0, 1, t) equals the t-weighted crossfade at 0.25, 0.5 and 0.75 (Quad InOut does not: 0.125 against 0.15625 at 0.25). 0.8 t² + 0.2 t³ is within 0.0076 of t^2.2 on 0..1 (0.75/0.25: 0.0041). The talk's own blend weights are garbled in the transcript.
• Not taken: the bounce and abs() variants (one line each would add little).

Math for Game Programmers: Dark Secrets of the RNG

• Speaker: not named (Hearthstone prototype; Direwolf Digital). Year not stated.
• Video: https://www.youtube.com/watch?v=J5qnnxFoBss
• Taken: shuffle bags with the 2k edge case, pity timers with a hard cap, no clock seeds players can time (Urban Dead), child seeds from the index path (deep echoes). .agents/skills/procgen/SKILL.md and a tested examples/csharp/src/Example.Core/Procgen/Draws.cs (ShuffleBag, PityRoll) with examples/csharp/tests/Example.Core.Tests/DrawsTests.cs.
• Measured (DrawsTests, seeded): a die over 7 kinds gave 6 in a row in 100,000 draws; a bag with one copy each gave 2 (k = 1, 2, 3 stay within 2k; the guard keeps them within k). A 1% drop: longest dry run 998 in 1,000,000 rolls; capped at 99 misses, 99 and a 1.58% rate; plus 0.1% a miss, 3.15%. Breaking the guard or the cap fails four tests.
• Not taken: nested loot tables (the skill's weighted Pick already nests) and broad echoes (left open in the talk).

Math for Game Programmers: Parallel Random Number Generation

• Speaker: Manny Koh as transcribed (Manny Ko), Activision. Year not stated.
• Video: https://www.youtube.com/watch?v=qO8FAQvlgX0
• Taken: the same output on any thread count, by drawing each item's randomness from a hash of the seed and its index (the kit's Seeds.Derive already is one). procgen, "Seeds that stay the same". A .NET run for the kit: 1,000 chunks with derived seeds gave the serial fingerprint on every parallel run; one shared generator behind a lock gave a different one each run.
• Not taken: LCG constants, leapfrogging and TEA on the GPU (the kit's generators are not LCGs).

How Cameras in Side-Scrollers Work

• Speaker: not named in the transcript (the developer of Mushroom 11). Year not stated.
• Video: https://www.youtube.com/watch?v=pdvCO97jOQk
• Taken: the vocabulary (camera window, edge and platform snapping, forward and dual forward focus, attractor rings, several players) mapped to Camera2D properties checked on 4.7.2, and speed-dependent smoothing (0.5 s fast, 2.5-3 s slow). .agents/skills/camera/SKILL.md section 9.
• Not taken: the speed-up push zone and projected focus (no Godot mapping worth a line); a camera flow test.

Game Feel: Why Your Death Animation Sucks

• Speaker: Nicolae Barbecem as transcribed (Nicolae Berbece, "Xelu"; Those Awesome Guys). Year: about 2015, inferred ("the new lens flare of 2015").
• Video: https://www.youtube.com/watch?v=pmSAG51BybY
• Taken: feedback as information players notice without looking; a fading death mark; rumble. .agents/skills/game-juice/SKILL.md, checklist rows "Marks" and "Rumble" (the haptics rules themselves are in input).
• Not taken: animating from part sheets with per-frame transforms (an art pipeline choice); movement-sound advice already in game-juice and game-audio.