docs: finalize brainstorming session with idea organization and implementation roadmap

_bmad-output/brainstorming/brainstorming-session-2026-04-12-001.md

@@ -1,5 +1,7 @@
 ---
-stepsCompleted: [1, 2, 3]
+stepsCompleted: [1, 2, 3, 4]
+session_active: false
+workflow_completed: true
 inputDocuments: []
 session_topic: 'Classic 2048 web game recreation'
 session_goals: 'Faithful recreation of original 2048 gameplay with local scoring, built as exploration project'
@@ -136,3 +138,70 @@ techniques_completed: ['First Principles Thinking', 'Mind Mapping', 'Morphologic
 - `game.js` — Core game logic (grid state, move, merge, spawn, win/lose detection)
 - `input.js` — Keyboard and touch/swipe handler
 - `storage.js` — localStorage persistence (game state + best score)
+
+## Idea Organization and Prioritization
+
+### Thematic Organization
+
+**Theme 1: Core Game Engine** — Pure logic, no UI
+- 4x4 grid state management (create, read, check empty cells)
+- Tile spawning (random empty cell, 90/10 value split)
+- Slide + merge algorithm (leading-edge, once-per-move rule)
+- Score calculation (add merged tile value)
+- Win detection (2048 tile created) + continue mode
+- Game over detection (no moves available)
+
+**Theme 2: Presentation Layer** — What the player sees and feels
+- Tile rendering with 12-tier color system
+- Dynamic font sizing (55/45/35px by value)
+- Glow effects on 128+ tiles
+- 4 animations: slide (100ms), pop (200ms), bounce (200ms), score float (600ms)
+- Win/lose overlay with fade-in
+- Responsive layout (500px desktop, 280px mobile)
+
+**Theme 3: Player Interaction** — How the player controls the game
+- Keyboard: arrows + WASD + Vim (hjkl) + R restart
+- Touch: single-finger swipe with 10px threshold
+- Modifier key blocking
+- "New Game" button, "Keep going" button
+
+**Theme 4: Persistence & Infrastructure** — Keeping state and shipping it
+- localStorage for game state (save after every move, clear on game over)
+- localStorage for best score (persists always)
+- Svelte + Vite + Tailwind build pipeline
+- GitHub Pages deployment
+
+### Prioritized Implementation Order
+
+| Priority | What | Why |
+|----------|------|-----|
+| 1 | Project scaffold (Vite + Svelte + Tailwind) | Foundation for everything |
+| 2 | Core game logic (`game.js`) | Can be tested without UI |
+| 3 | Grid + Tile rendering | See the game working |
+| 4 | Input handling (keyboard first) | Play the game |
+| 5 | Score display + best score | Track progress |
+| 6 | Animations (slide → pop → bounce) | Polish the feel |
+| 7 | Touch/swipe support | Mobile playability |
+| 8 | Win/lose overlays | Complete game loop |
+| 9 | localStorage persistence | State survives refresh |
+| 10 | Responsive design + deploy | Ship it |
+
+## Session Summary and Insights
+
+**Key Achievements:**
+- Complete understanding of original 2048 mechanics from source code research
+- Full component breakdown covering all 6 system areas
+- Definitive tech stack decision: Svelte + JS + Tailwind + Vite + GitHub Pages
+- Clear 10-step prioritized implementation roadmap
+
+**Session Reflections:**
+- First Principles research provided implementation-ready specs (exact colors, timings, merge rules)
+- Mind Mapping ensured no component was overlooked across logic, rendering, input, UI, and infra
+- Morphological Analysis made tech decisions systematic rather than arbitrary
+- The combination of these three techniques moved efficiently from "what is 2048?" to "how exactly do we build it?"
+
+**Next Steps:**
+1. Create a PRD or product brief from this brainstorming output
+2. Design the technical architecture based on the component structure
+3. Create epics and stories following the prioritized implementation order
+4. Begin development with project scaffolding