Claude-Code-Game-Studios/.claude/docs/templates/vertical-slice-report.md

Vertical Slice Report: [Concept Name]

Date: [YYYY-MM-DD] Slice Duration: [N days] Target Scope: 3–5 minutes of polished, continuous gameplay Source GDD: design/gdd/game-concept.md

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Validation Question

[The full game loop question this build was proving — both experience AND feasibility: "Does a player, starting from nothing, experience [core fantasy] within [N] minutes, without developer guidance — and can we build one such loop in [X] days at representative quality?"]

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Scope Built

[Systems implemented, art quality level, what was intentionally omitted.]

Systems included:

• [System 1]
• [System 2]
• [...]

Art/audio quality level: [Placeholder / Representative / Near-shipping] Shortcuts taken deliberately: [List] What was cut from original scope: [List]

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Build Velocity Log

[Day-by-day record of what was completed. This is your real production rate data — use it in sprint planning.]

Day	Completed
Day 1	[What was built]
Day 2	[What was built]
Day 3	[What was built]
...	...

Total elapsed: [N days] for [scope summary] Velocity estimate: [N hours per equivalent scope unit — e.g., "1 day per combat encounter, 0.5 days per UI screen"]

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Playtest Results

Attribute	Value
Total sessions	[N]
Internal testers	[N]
External testers	[N — people who had not seen the game, if available]
Avg session length	[N minutes (target: [N] minutes)]
Time to first meaningful action	[N seconds (target: [N] seconds)]

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Observations

[Specific, non-opinion observations from playtest sessions. Quote testers where useful.]

Where testers succeeded without guidance:

• [...]

Where testers were confused or stuck:

• [...]

Emotional reactions observed:

• [...]

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Metrics

Metric	Target	Actual
Time to first meaningful action	[N sec]	[N sec]
Session length	[N min]	[N min]
Critical fun blockers found	0	[N]
Pipeline blockers found	0	[N]
Architecture surprises	0	[N]

Feel assessment: [Specific — "combat feedback weak; no impact sound on hit" not "felt rough"]

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Recommendation: [PROCEED / PIVOT / KILL]

[One paragraph with evidence — reference the validation question directly. Did a player experience the core fantasy within the target time, without developer guidance? Can the team build at this quality on the projected schedule?]

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If Proceeding

Production requirements (what must change from slice to production):

• [e.g., "Replace placeholder art with shipped assets"]
• [e.g., "Combat system needs 2 more weapon types"]

Architecture adjustments needed:

• [ADR to update or create]

Sprint velocity estimate based on slice data:

• [e.g., "1 day per enemy type, 2 days per level section, 0.5 days per UI screen"]

Scope adjustments from original design:

• [What the slice revealed about the true production scope]

Performance targets: [Confirmed / Revised — list changes if revised]

Playtest note: Run /playtest-report to structure additional session data before running /gate-check pre-production.

Next steps:

1. /gate-check pre-production — formally advance to Production
2. /create-epics layer:foundation — plan Foundation layer epics
3. /create-epics layer:core — plan Core layer epics
4. /sprint-plan — use velocity data from this report in the estimate

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If Pivoting

[Which GDDs need revision and why — be specific about the failure mode observed.]

Systems requiring GDD revision: [List] Architecture decisions to revisit: [List — use /architecture-decision to update] Core loop change needed: [What specifically to change]

Next steps:

1. /design-system [mechanic] — revise affected GDDs
2. /architecture-decision [decision] — address architecture issues
3. /vertical-slice — re-validate after revisions

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If Killing

[Why the full game loop does not work at this quality level. What specifically prevented the player from experiencing the core fantasy. What to do instead.]

Next step: /brainstorm to explore a new direction, or /prototype [new-concept] to test a different concept cheaply before investing in another vertical slice.

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Lessons Learned

• What assumptions were broken by building to near-production quality? [...]

• What surprised us about the pipeline or architecture? [...]

• What would we change about the slice scope if we ran this again? [...]

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Vertical slice code location: prototypes/[concept-name]-vertical-slice/ This code is reference material only. Production implementation is written from scratch. Never import or refactor this code into production.