MSW New-Game Planning Mode (msw-planning)

Purpose

When the user is at the "I want to make a game like this" stage, turn it into what to build + how to build it in MSW: a guided session produces a GDD/roadmap, then the skill guides the phased build — detailed Phase plans, progress tracking, and plan revisions — until each milestone's build is ready to enter full implementation. Someone who doesn't know game design can just follow the questions; for those who do, it documents decisions fast.

Core principles (why it works this way)

• Catalog grounding: MSW is 2D · mLua (a Lua-extension scripting language) · cross-platform, so the space of "what you can build" is bounded. Map a vague idea onto the real genres/map-types/mechanics in references/genre-catalog.md to get a feasible plan. Planning from generic game knowledge alone leads to designs MSW can't realize.
• Right-size the build: the catalog gives a build-effort hint (Low / Medium / High) per genre — a signal, not a verdict (baseline 1–5 maps · 10–20 units/items · basic-to-intermediate mLua; tower defense sits at the top of comfortably-solo). Use it to set expectations, not to refuse a genre. Size the first build by build-effort + scope (maps/content), never by a calendar/development-time estimate — the skill can't know the user's skill level or available hours, so it doesn't promise 'this takes N days/weeks.' When the user's ambition is large (a High-effort genre, or many systems/maps, or "I want everything"), don't plan it all at once — scope the first build down to a small playable core (MVP) and push the rest to later Phases. This applies to any genre.
• Single pass (no ping-pong) + one direction check: limit user touchpoints to STEP 1 (batched questions) and STEP 3 (direction check) — don't keep asking back in between. But never skip STEP 3 (direction check) before writing the GDD: don't just flash the grounding result and jump straight to the GDD. Once the direction is confirmed, produce the deliverable immediately.
• Standardized deliverable: drop the result into the fixed GDD structure (references/gdd-template.md) as markdown, so the implementation skills can pick it up and carry it to an MVP.
• Single home for "later": a GDD covers ONLY its own milestone. Anything beyond it — cut features, later-milestone ideas, a "let's do that someday" request mid-discussion — is recorded the moment it surfaces in the standing milestone roadmap (Docs/<game>-Roadmap.md: a future-milestone slot, or its Backlog when the timing is unknown), and never parked in the GDD. One home, no duplication: the roadmap owns everything beyond the current milestone; the GDD owns everything inside it.
• Carry the project forward: after each deliverable, propose the next step first (e.g., "Shall I write the Phase 1 detailed plan next?"). Proceed if the user wants it, stop if they say stop — it's a suggestion, not a push. (This differs from endless mid-document ping-pong — it connects the flow between deliverables.)
• Decision gates = selectable choices, not free text: at each user decision gate — STEP 3 direction check, the Phase handoff (implement now vs write the next-Phase plan), and the soft Phase gate — present the options as a structured selectable choice via the agent's multiple-choice UI when available (e.g., Claude Code's AskUserQuestion), so the user clicks an option instead of typing a free-text reply. Mark the recommended option but don't force it; if the agent has no such UI, fall back to a clearly enumerated prose choice.