Hargob
Game Design Document
| Author | Jorge M. Castillo |
| Working title | Hargob, from Harmonic Goblin |
| Genre | Rhythm action |
| Theme | Dark-fantasy, magical sci-fi |
| Engine | Phaser mechanics laboratory; Godot 4/C# production game |
| Team size | Solo |
| Platform | Browser prototype; Itch.io / Steam target |
| Age-rating goal | T–M for suggestive drug use and cartoon violence |
Full Game Vision
High Concept
Hargob is a rhythm-action game with an emergent musical soundtrack. Enemy movement, telegraphs, hitboxes, and recovery share the same musical timing. The player learns an enemy's phrase, dodges it, and answers on beat.
- The enemy telegraphs an attack phrase.
- The player dodges spatially and, ideally, rhythmically.
- A rhythmic dodge builds Momentum and opens a counter window.
- The player counters immediately or banks Momentum.
- A counter releases all stored Momentum on impact.
Lore and Background
For thousands of years, the Knights of the Eastern Salts have expanded through Arc-Harmonic Technomancy, the study and arcane manipulation of universal rhythms such as planetary orbits, tides, and organism lifecycles.
One of their machines unintentionally accelerates the tide cycle, washing strange deep-sea creatures and vibrant, humming Sea Slugs onto the coast. After eating the contaminated slugs, Hargob and several coastal goblins develop a never before seen Arcane Harmonic Intuition: the ability to perceive attacks, movement, and magic as musical structure.
This intuition is the in-world basis of the rhythm-action gameplay. Hargob can hear and feel an enemy's movement, anticipation, attack, and recovery as parts of a phrase.
Aesthetic tone: Hargob ventures through a shifting coastal region to challenge the Knights for their oppression of the goblins. Coastal creatures encountered along the way are warped and naturally very aggressive as a result of the tidal acceleration. The goblins are naturally goofy and unserious, contrasting with the Knights' grand, self-important character. Sea Slugs carry the same tonal contradiction: they are the contaminated source of Hargob's power, but are also treated as cheerfully delicious rewards.
Eating enough slugs leaves a goblin profoundly stoned. While lying back and staring upward, they see the sky's dome flatten into a projection and hear the stars speak. This is communion with The Flat One: simultaneously the flattened sky, a fourth-wall reference to the display, and a goblin's dim awareness of The Player watching and guiding them.
Player Experience
Hargob should feel like playing a feral but feeble little guy: weak in direct exchanges but willing to charge into danger, redirect rhythmic energy, and unleash devastating counters.
Combat should equally reward:
- Learning an enemy's rhythm and patterns.
- Executing spatial and rhythmic dodges.
- Feeling tension rise with Momentum before a counter releases it.
Ordinary action-game play remains valid, but rhythmic mastery wins faster and intensifies the audiovisual response.
Core Combat Systems
Musical Transport
Combat uses one authoritative audio clock. Gameplay queries beat-relative musical position rather than maintaining an unrelated combat timer.
Movement, Dodge, and Counter
Movement is continuous and never waits for a beat.
| Result | Spatial requirement | Rhythmic requirement | Outcome |
|---|---|---|---|
| Full rhythmic dodge | Leave the active hitbox | Dodge inside the timing window | Avoid damage, gain Momentum, arm the next-beat counter |
| Spatial-only dodge | Leave the active hitbox | Miss the timing window | Avoid damage, gain no Momentum, arm no counter |
| Failed dodge | Remain inside the active hitbox | Any timing | Take damage and reset Momentum |
Hargob may attack at any time. Outside an earned counter window, the enemy blocks but still receives chip damage. During the next-beat counter window, the player may attack immediately or skip it and retain Momentum for a stronger later counter. Every counter consumes all stored Momentum, with damage and impact scaling to the amount released.
Momentum
Momentum represents Hargob redirecting rhythmic energy and taking control of the musical exchange.
| Gain | Loss and use | Effects |
|---|---|---|
| Full spatial-and-rhythmic dodges | Damage resets it; inactivity or disengagement causes smooth decay; counters consume it | Counter damage and reaction; percussion and audiovisual layering; animation and particles |
Spatial-only dodges and ordinary blocked attacks add no Momentum. Presentation changes smoothly rather than jumping between visible tiers.
Incant System
Incants are a later full-game alternative use for a completely full Momentum meter:
Full Momentum → Draw → Momentum Pinned → Select and Perform → Resolve → Momentum Depleted
Core rules:
- A separate draw button produces three Incants from a fixed deck of 10.
- The three cards occupy three stable buttons dedicated exclusively to Incants.
- Drawing pins Momentum rather than immediately depleting it; Hargob may keep moving.
- Selecting a card locks its recognizer, plays its opening accent, and begins its phrase. The player cannot switch mid-phrase.
- Incant phrases use only the three dedicated buttons. Movement, attacks, counters, and dodges never count as phrase inputs.
- Dodging or countering cancels or interrupts the Incant state. The exact same three-card offer remains reserved for the next draw, intentionally allowing the player to peek.
- Using an Incant depletes the pinned Momentum. How other cancellation actions affect Momentum remains a tuning question.
| Outcome | Effect | Cards |
|---|---|---|
| Success | Correct structure and acceptable timing; full effect | Discard the used card; return the two unused cards |
| Weak Success | Correct structure with imprecise timing; reduced effect | Discard the used card; return the two unused cards |
| Failure | Invalid or expired sequence | Preserve the same three-card offer |
| Interrupted | Hit, dodge, counter, or other interruption | Preserve the same three-card offer |
| Cancelled | Draw cancelled before resolution | Preserve the same three-card offer |
After success, the next draw comes from the remaining deck. When the draw pool empties, shuffle the discard pile back into it.
The recognizer compares dedicated-button inputs against beat-relative positions and tolerances. Inputs grade as Perfect, Good, Early, Late, Missed, or Incorrect; slightly early inputs may buffer into the valid window.
| Melody type | Definition |
|---|---|
| Static | Always the same phrase |
| Generative | Some notes are probabilistic; no runtime LLM |
| Expressive | Any performance satisfying a unique rhythmic condition |
No two Incants may share an identical phrase or recognition condition.
| Category | Possible effects |
|---|---|
| Offensive | Charged strikes, projectiles, area attacks, counters, status effects, phrase disruption |
| Defensive | Shields, healing, damage conversion, temporary invulnerability, Momentum preservation |
| Harmonic | Temporary tempo changes and altered enemy phrase structure |
Feedback Principles
Feedback must distinguish enemy intent, spatial versus rhythmic dodge results, counter availability, Momentum state, blocked versus counter damage, and encounter outcomes. Sound, animation, hit reactions, particles, screen effects, HUD, color-independent symbols, and optional controller response may reinforce those distinctions. The most polished event should be a Momentum-scaled counter.
Overall Direction
- Multiple enemies with distinct musical identities: Crab, Brute, Ghost, Wendigo, and Troglodyte.
- Authored motifs assembled into changing phrases and a larger musical difficulty grammar.
- Sea Slugs as persistent reward and currency.
- A Hades-inspired run and base-camp structure.
- Communion with The Flat One to purchase Incants.
These establish the intended identity, not the current prototype scope.
Current Prototype
Prototype Contract
The Phaser prototype tests whether one readable musical attack can produce a satisfying dodge, Momentum build, and counter release.
| Area | First-pass commitment |
|---|---|
| Flow | Main menu → arena → victory or game over → main menu |
| Content | Hargob, one coastal arena, one crab template enemy |
| Player actions | Continuous movement, one dodge, one basic attack |
| Phrase | One static 4/4 loop: beat 3 telegraph; “and” of 3 hold; beat 4 attack; next bar beat 1 counter |
| Health | The third connected enemy attack ends the encounter and resets to the menu |
| Momentum | About one-third per full rhythmic dodge; reset on damage; smooth decay; fully consumed by a counter |
| Damage targets | 10 blocked basic attacks, about 5 low-Momentum counters, or 1 full-Momentum counter |
| Guard | Ordinary attacks deal chip damage and have no recovery penalty |
| Audio | Raw Web Audio API percussion communicates beat, anticipation, impact, Momentum, and release |
The template enemy blocks ordinary attacks, uses no adaptive AI, and repeats the same phrase every measure. Exact BPM, timing windows, movement speed, dodge distance, decay rate, damage, and feedback curves remain tuning variables.
Technical Direction
| System | Responsibility |
|---|---|
| Musical Transport | Own tempo, bar, beat, subdivision, and timing windows using the audio clock |
| Enemy Phrase Controller | Schedule telegraph, hold, attack, and recovery |
| Combat Controller | Resolve hitboxes, dodges, guard, counters, health, and outcomes |
| Momentum Controller | Resolve gain, decay, reset, consumption, damage, and intensity |
| Audio Renderer | Generate percussion and Momentum-dependent layers |
| Presentation and Scene Flow | Render feedback and move between menu, arena, victory, and game over |
Musical transport remains independent of rendered frame timing to prevent audio and combat drift.
Out of Scope
The first prototype excludes multiple enemies or arenas, multiple or procedural phrases, dynamic musical grammar, Incants, progression, runs, base camp, the Sea Slug economy, narrative campaign content, the Knights' stronghold, and production latency calibration.
Development Agents
Development work separates deterministic transformations from agent judgment. Exporters, scaffolders, schema checks, timeline generation, telemetry capture, metric calculation, and output guardrails are ordinary code. Agents interpret, create, prioritize, and propose; they do not replace those tools.
Enemy Phrase Production Agents
| Agent | Judgment task | Token cap | Inputs | Outputs |
|---|---|---|---|---|
| Rhythmic Phrase Designer | Define an enemy's musical identity and draft phrase intent. | 6,000 | Approved enemy brief, difficulty, BPM, phrase length, musical constraints | Musical identity brief and draft beat-relative phrase |
| Encounter Choreographer | Assign combat meaning and arrange a spatially and rhythmically playable sequence. | 7,000 | Validated phrase package, movement values, timing rules, difficulty target | Encounter candidate, risk report, playtest questions |
| Phrase Playability Reviewer | Interpret validation evidence and judge readability, pacing, and unresolved playability risks. | 5,000 | Encounter candidate, deterministic validation report, inspection timeline, success criteria | Cited review, ranked risks, revision request or human-review recommendation |
Combat Playtest and Balance Agents
| Agent | Judgment task | Token cap | Inputs | Outputs |
|---|---|---|---|---|
| Telemetry Interpreter | Turn prepared metrics into cited evidence while identifying anomalies, confounders, and data limitations. | 4,000 | Prepared telemetry, configuration groups, calculated metrics, data-quality report, success criteria | Evidence findings with metric or session references and caveats |
| Player Experience Analyst | Interpret what players may be learning or feeling without treating inference as fact. | 4,000 | Evidence findings, player feedback, timestamp-aligned gameplay video, success criteria | Ranked experience hypotheses, alternatives, and evidence references |
| Balance Analyst | Propose the smallest useful and reviewable tuning experiment. | 5,000 | Evidence, experience hypotheses, current semantic tuning, success criteria | At most two proposed tuning changes with baselines, units, evidence, and risks |
| Experiment Planner | Make the proposed adjustment falsifiable. | 3,000 | Evidence, hypotheses, tuning proposal | Control and variant, measures, stop conditions, and decision rule |
Phaser and Godot may produce the same future engine-neutral telemetry contract through separate adapters. Deterministic preprocessing validates and groups sessions, calculates metrics, and reports data quality. Deterministic postflight checks evidence references and tuning limits, then writes proposed artifacts under ignored output directories. Agents never apply tuning or edit source.
The coordinated loop is:
Human brief → phrase agents → human Ableton authoring → deterministic export
and validation → human playtest → deterministic evidence preparation →
playtest agents → human approval
Players experience the result through distinct musical enemy attacks, synchronized audio and combat events, clearer timing, and evidence-driven balance improvements.