A complete game design document for an addictive potato card battle game. Part of the Hot Potato Games design series.
🥔⚔️ Welcome to Spud Brawl
Genre: Card Battle / Auto-Battler
Platform: Web (HTML5 Canvas + vanilla JavaScript)
Tagline: Build your deck. Deploy your spuds. Dominate the table.
Spud Brawl is a fast-paced card battler where you collect, deploy, and upgrade potato warriors to fight through increasingly tough enemy waves. Think Slay the Spire meets potato universe — with an elemental triangle, boss battles, and deck building.
🔄 The Core Loop
Every 30 seconds, a player will:
- Draw 2 cards from their deck
- Deploy potato warriors to 3 battle slots (spending Starch energy)
- Watch the battle play out automatically — cards attack based on speed
- Collect starch points from defeated enemies
- Upgrade or buy new cards between rounds
It's fast. It's strategic. And you'll say "one more round" about 47 times.
⚡ Key Mechanics
1. The Elemental Triangle
Three potato elements in a rock-paper-scissors system:
- 🔥 Baked beats 🧊 Frozen (melts them)
- 🧊 Frozen beats 🌿 Sprouted (frost kills growth)
- 🌿 Sprouted beats 🔥 Baked (growth smothers fire)
Deploying cards with elemental advantage deals 1.5x damage. Reading your opponent's elements and countering them is the heart of the strategy.
2. Starch Energy System
Every card costs Starch to play. You start each round with 3 Starch and gain +1 max per round (capping at 10). Cheap cards (1-2 Starch) are weak but let you flood the board. Expensive cards (7-10 Starch) are devastating but leave you exposed early rounds. Managing your economy is everything.
3. Potato Abilities
Each card has a unique passive ability:
- Mash Shield — Absorbs the first hit completely
- Fry Burst — Deals damage to ALL enemies on death
- Sprout Heal — Heals adjacent allies +1 HP per turn
- Chip Shot — 30% chance to attack twice
- Peel Armor — Reduces incoming damage by 1
4. Deck Building
After every 3 rounds, visit the Spud Shop:
- Buy new cards with starch points
- Sell unwanted cards for half price
- Combine 3 identical cards into a powered-up version (bronze → silver → gold)
5. Boss Battles
Every 5th round features a boss:
- King Russet (Round 5) — Massive HP, hits all 3 player slots every turn
- The Fry-nator (Round 10) — Attacks twice per turn with random elements
- Lord Mash (Round 15) — Heals every turn, must burst down fast
- Tater Tot Swarm (Round 20) — Floods the board with tiny attackers
📈 Progression
| Phase | Rounds | What Happens |
|---|---|---|
| Tutorial | 1-5 | Simple battles, learn elements |
| Strategy | 6-10 | Full 3v3, smarter enemies |
| Abilities | 11-15 | Enemies use abilities, combos matter |
| Boss Rush | 16-20 | Build a perfect deck or get mashed |
| Endless | 21+ | Leaderboard mode — how far can you go? |
🎨 Art Direction
Retro hand-painted card art with thick outlines. Think Slay the Spire meets a children's book. Each potato character has exaggerated expressions — angry baked potatoes with steam, frozen fries with icicle beards, sprouted potatoes with vine tentacles.
Color palette: Warm earth tones (browns, golds, greens) with elemental accents. The battle board is a rustic wooden tavern table viewed from above. UI uses parchment textures with wooden card frames.
🔊 Sound Design
- Card deploy: Satisfying thwack of card on wood
- Baked attack: Sizzling fire burst
- Frozen attack: Crystalline ice shatter
- Sprouted attack: Vine whip snap
- Card death: Comedic splat
- Music: Tavern folk — lute, fiddle, hand drum. Playful but not frantic.
💰 XRP Integration Ideas
- Daily Tournaments: 1 XRP entry, winner-takes-pool
- Premium Card Packs: 5 XRP for 3 guaranteed-rare cards
- Cosmetic Skins: Gold card backs, animated borders (2-10 XRP)
- Season Pass: 50 XRP per season for exclusive content
Free-to-play core is always complete. XRP adds flair, not power.
🎯 MVP Scope (1-2 Day Build)
Must have:
- 12 unique cards (4 per element) with stats + abilities
- 3-slot battle board with auto-combat
- Elemental advantage system
- 10 rounds of increasing difficulty
- Basic deck building between rounds
- Score tracking with local high scores
Nice to have (day 2): Card combination, boss battle, sound effects, card animations
🔗 The Prompt Chain — Build This Game with AI
Here's the magic: a sequence of 5 prompts that a coding AI agent can execute to build the entire game from scratch. Each prompt is self-contained and builds on the previous output.
Prompt 1: Project Setup + Core Game Loop
Sets up the project structure, card data model (12 cards across 3 elements), the game state machine (TITLE → DEPLOY → BATTLE → LOOT → SHOP), and a basic playable loop with placeholder graphics. Tech: vanilla JS + Canvas.
Prompt 2: Game Mechanics + Player Interaction
Implements the full combat engine — elemental advantages, card abilities, Starch energy system, enemy AI that scales by round, deck management, and the Spud Shop with buy/sell/combine mechanics.
Prompt 3: Art Integration + UI
Replaces placeholders with polished Canvas-drawn visuals — card frames with element colors, simple potato character art using Canvas primitives, animated battle board, slide/flash/shrink animations, and complete UI screens.
Prompt 4: Polish, Sound, Scoring
Adds Web Audio API sound effects (generated with oscillators, no external files), scoring system with combos and multipliers, boss implementations, screen shake, particle effects, damage numbers, and responsive design for mobile.
Prompt 5: Deploy-Ready Build
Final pass — meta tags, favicon, high score persistence, share button, keyboard shortcuts, pause menu, and a testing checklist. Output: a single directory that works by opening index.html. No dependencies.
Full prompt chain with complete implementation details available in the Hot Potato Games developer docs.
🎮 The Card Roster
🔥 Baked Element
| Card | ATK | HP | Ability | Vibe |
|---|---|---|---|---|
| Baked Warrior | 2 | 5 | Mash Shield | Stalwart front-liner with glowing cracks |
| Chip Rogue | 4 | 2 | Chip Shot | Glass cannon, dual fire daggers |
| Wedge Berserker | 3 | 4 | Fry Burst | Goes out with a bang |
| Ember Spud | 3 | 3 | Peel Armor | Balanced all-rounder |
🧊 Frozen Element
| Card | ATK | HP | Ability | Vibe |
|---|---|---|---|---|
| Fry Mage | 3 | 3 | Chip Shot | Spellcaster with ice crystal staff |
| Hash Guardian | 1 | 7 | Peel Armor | Unkillable frost wall |
| Tot Healer | 1 | 4 | Sprout Heal | Keeps your team alive |
| Frost Fry | 2 | 5 | Mash Shield | Absorbs the opening blow |
🌿 Sprouted Element
| Card | ATK | HP | Ability | Vibe |
|---|---|---|---|---|
| Root Titan | 2 | 6 | Mash Shield | Ancient and immovable |
| Seedling Scout | 4 | 2 | Chip Shot | Fast and fragile |
| Vine Druid | 2 | 4 | Sprout Heal | Self-sustaining healer |
| Bloom Spud | 3 | 3 | Fry Burst | Explosive exit strategy |
Want to build this? The full prompt chain with detailed implementation specs is designed to be fed directly into a coding AI agent. One developer + one AI = playable game in a weekend.
Stay tuned for more game designs from Hot Potato Games. Next up: something multiplayer. 🥔