Blank-slate opportunity portfolio — 2026-08-26

Scope and evidence

This is a fresh portfolio. Second Truth, 科目B問題集, AI Banner, PENGIN Tools, 運命分岐炉 and their derivatives are excluded. No product was built, published, sold, or submitted for approval.

Live evidence used (official/primary sources, deliberately limited):

1. itch.io pricing: paid, free/PWYW, individually priced files, sales, bundles and early access are native; paid buyers retain ownership. This supports fast payment/download tests among indie-game creators and players, but does not prove demand for any particular item.
2. itch.io creator FAQ: hosting, payment, and page-view/download/purchase analytics are built in and listing is free. This makes a 72-hour behavioral test measurable without a custom site.
3. Gumroad fees: direct sales cost 10% + $0.50 plus processing, while Discover sales cost 30%; no monthly fee. Discovery cannot be treated as free distribution, so candidates need an audience location outside the listing itself.
4. Teachers Pay Teachers resource policy: educators already discover, buy, sell, and share original teaching resources under individual licenses. This confirms a paid-resource channel, not the need for a specific resource.
5. GitHub Marketplace overview: developers discover Actions and Apps there; Actions can be shared by anyone, while paid Apps require organization ownership. A free Action can test adoption quickly, but paid-App onboarding is too heavy for the first 72 hours.
6. Discord Server Shop: subscriptions/products have native checkout and a 90/10 split, but monetization requires community setup, MFA, review, payout onboarding, and thresholds. It is evidence of spend, but a reason not to make a new Discord community the initial channel.

Common scoring

Scores are 1–5: channel fit (C), one-day MVP (M), measurable in 72h (T), emotional novelty (E), revenue clarity (R), 30-day asset (A). “First 10” means ten relevant strangers reached through permitted public participation, not unsolicited DMs.

Twelve candidates across eight business types

1. Session Spark — collaborative micro-game (interactive game)

• Customer/problem/spend: online tabletop GMs whose session starts flat; they already buy one-shots, encounter decks, and VTT add-ons.
• 10-second artifact: a browser scene with three glowing player buttons; simultaneous choices collide into one surprising complication card.
• Existing gathering place: itch.io physical-games browsing, relevant public tabletop game jams, and opt-in playtest threads in tabletop-design communities.
• First 10: enter one currently open, relevant itch.io jam; post a rules-compliant 30-second GIF and invite ten public playtest sign-ups through the jam feedback thread.
• One-day MVP: 12 original dilemmas, room code, three votes, instant reveal; no login or saved personal data.
• 72-hour behavior: 10 room starts, 4 rooms with 3 participants, 2 replays or shared room links.
• Revenue: free 12-scene demo; $6 themed expansion on itch.io.
• Share/revisit: the group’s unexpected combined result is screenshot-worthy; new weekly scene pack creates return.
• Scores: C5 M4 T5 E5 R4 A4 = 27.

2. Tiny Museum of Us — shared memory exhibit (social creation)

• Customer/problem/spend: close friends or couples tired of generic photo dumps; they buy photo books, cards, and novelty gifts.
• 10-second artifact: three private prompts become a tiny walkable pixel museum with labeled objects.
• Gathering: itch.io interactive-fiction/jam audiences and public cozy-game creation communities with feedback threads.
• First 10: submit to a relevant open cozy/interactive jam and invite public commenters to create a two-person exhibit using anonymous prompts.
• MVP: local-only three-object museum, shareable static postcard export; no account or cloud storage.
• 72-hour behavior: 10 completions, 3 postcard exports, 2 second exhibits.
• Revenue: $5 desktop download; later $2 visual-room packs.
• Share/revisit: personalized exhibit is inherently showable; anniversaries and trips create repeat use.
• Scores: C4 M4 T4 E5 R4 A4 = 25.

3. One-Minute Mystery Club — asynchronous party puzzle (episodic game)

• Customer/problem/spend: small Discord friend groups wanting a recurring low-commitment activity; they buy party games and puzzle subscriptions.
• 10-second artifact: one illustrated crime scene, three clues, and a dramatic group-vote reveal in under a minute.
• Gathering: itch.io puzzle/visual-novel tags and open game-jam feedback channels; Discord is the use context, not the acquisition plan.
• First 10: publish a free jam-compatible episode only after a future approval; recruit playtesters from the jam’s opt-in feedback exchange.
• MVP: 5 original cases in a self-contained HTML file with shareable result text.
• 72-hour behavior: 15 case starts, 5 finishes, 3 copied result cards.
• Revenue: $4 monthly five-case season sold as download; no Server Subscription dependency.
• Share/revisit: group disagreement is the story; weekly answer reveal drives return.
• Scores: C4 M5 T5 E4 R4 A4 = 26.

4. NPC Alibi Board — printable improvisation prop (creator tool)

• Customer/problem/spend: mystery-RPG GMs who lose momentum tracking contradictory NPC statements; they buy GM aids and printable props.
• 10-second artifact: a detective-board sheet where folding one flap reveals which testimony cannot coexist.
• Gathering: itch.io physical-games/print-and-play tags and mystery-RPG jam pages.
• First 10: release one free scenario into an eligible jam and exchange public playtests with ten entrants.
• MVP: one original A4 board, 8 testimony slips, 20-minute rules.
• 72-hour behavior: 10 downloads, 3 printed-play confirmations, 2 session photos voluntarily posted.
• Revenue: $7 pack of six cases; future themed packs.
• Share/revisit: physical reveal photographs well; each case is replayed with new groups.
• Scores: C5 M5 T4 E4 R4 A4 = 26.

5. Classroom Debate Dice — low-prep speaking warm-up (education resource)

• Customer/problem/spend: middle-school language teachers needing safe, fast speaking prompts; they already buy teacher-authored worksheets/resources.
• 10-second artifact: roll topic, stance, and twist; a projector-ready 60-second debate appears.
• Gathering: Teachers Pay Teachers search and public teacher resource-sharing groups that explicitly allow creator feedback.
• First 10: offer a free 12-prompt sampler via a relevant public resource-feedback thread, asking educators to report whether students completed one round.
• MVP: original web dice plus printable fallback, 36 age-appropriate combinations.
• 72-hour behavior: 10 sampler opens, 3 classroom/club trials, 2 saves/bookmarks.
• Revenue: $5 full 180-prompt licensed resource on TpT; school license later.
• Share/revisit: amusing twist combinations prompt teacher sharing; repeatable bell-ringer.
• Scores: C4 M5 T4 E4 R5 A5 = 27.

6. Mood-to-Motion Cards — animation practice generator (education/creative)

• Customer/problem/spend: beginner animators who stall choosing exercises; they buy prompt packs and courses.
• 10-second artifact: “jealous + balloon + 12 frames” instantly becomes a tiny animation challenge with a share card.
• Gathering: itch.io game-assets/tools, animation challenge hashtags, and opt-in animation community prompt threads.
• First 10: join one public weekly challenge with an original sample animation and link the free generator where links are allowed.
• MVP: 120 curated combinations and PNG challenge-card export, no AI imagery.
• 72-hour behavior: 20 rolls, 5 exports, 2 posted animations linking the prompt.
• Revenue: $6 expanded deck plus monthly themed packs.
• Share/revisit: every completed animation cites a fun constraint; daily random prompt.
• Scores: C4 M5 T5 E5 R4 A5 = 28.

7. Patch Note Postcard — release-story generator (developer utility)

• Customer/problem/spend: solo game developers whose updates are ignored; they buy launch and community tools.
• 10-second artifact: paste terse patch notes and get a playful before/after postcard—not ad creative—with a changelog link.
• Gathering: GitHub Marketplace, itch.io devlogs, and public indie-dev release threads.
• First 10: publish a free Action later and request opt-in installs in a GitHub Discussions showcase/feedback thread; no repo scraping or DMs.
• MVP: deterministic Markdown parser with three original postcard themes and local SVG output.
• 72-hour behavior: 5 external workflow runs, 3 generated cards, 1 repeat release.
• Revenue: free Action; $19 one-time theme license sold separately.
• Share/revisit: every release creates a new card; cards point back to the project.
• Scores: C4 M4 T5 E4 R3 A5 = 25.

8. README Time Capsule — project-history collectible (developer media tool)

• Customer/problem/spend: maintainers who want contributors to feel project history, while current changelogs are dry; they pay for repo productivity tools.
• 10-second artifact: a single SVG “then → now” skyline built only from repository release metadata.
• Gathering: GitHub Marketplace and public open-source maintainer forums with showcase categories.
• First 10: ask ten maintainers in an opt-in “show your project” thread to run the Action and share the SVG; do not contact them privately.
• MVP: Action reading local git tags, producing an SVG without network or telemetry.
• 72-hour behavior: 5 external runs, 2 committed SVGs, 1 star/fork.
• Revenue: free adoption; $29 organization theme pack later (paid App only after validation).
• Share/revisit: visible history is a badge contributors show; updates each release.
• Scores: C4 M5 T5 E5 R2 A5 = 26.

9. Quiet Quest Calendar — analog micro-adventure (printable lifestyle)

• Customer/problem/spend: remote workers wanting novelty without another habit tracker; they buy calendars, stationery, and self-care printables.
• 10-second artifact: scratch/fold today’s square to reveal a harmless five-minute “notice something blue, rename it” quest.
• Gathering: Etsy printable browsing and public stationery/planner challenge communities.
• First 10: run a seven-day public challenge in a community that permits prompts, with one static preview and opt-in download.
• MVP: seven original quests, printable A4 calendar, phone wallpaper.
• 72-hour behavior: 15 downloads, 5 completed-quest shares, 3 day-two returns.
• Revenue: $4 monthly pack or $18 annual set via Gumroad/Etsy.
• Share/revisit: each quest yields a personal photo/caption; daily reveal creates return.
• Scores: C4 M5 T5 E5 R4 A4 = 27.

10. Soundless Karaoke — caption performance game (party/accessibility)

• Customer/problem/spend: friends in quiet spaces or mixed-hearing groups wanting expressive play; they buy party-game downloads.
• 10-second artifact: silently perform an original absurd caption while others choose its hidden emotion.
• Gathering: itch.io accessibility and party-game jams plus opt-in playtest exchanges.
• First 10: enter an applicable jam, offer browser play, and exchange ten structured playtests publicly.
• MVP: 40 original caption/emotion pairings, pass-and-play scoring, no copyrighted lyrics or audio.
• 72-hour behavior: 10 sessions, 4 multiplayer completions, 3 result screenshots.
• Revenue: $5 full 200-card version; $3 theme packs.
• Share/revisit: performances are funny without recording anyone; rotating captions encourage replay.
• Scores: C5 M5 T5 E5 R4 A5 = 29.

11. Object Oracle Studio — still-life storytelling activity (creative kit)

• Customer/problem/spend: sketch clubs and journaling groups seeking fresh communal prompts; they buy prompt books and workshop kits.
• 10-second artifact: photograph three ordinary objects locally; choose—not recognize—their roles, then receive a printable “museum label” story frame.
• Gathering: public urban-sketching/journaling challenge groups and itch.io tools.
• First 10: host a rules-compliant public #ThreeObjects challenge and invite ten opt-in submissions through the challenge thread.
• MVP: local image placement, manual role choices, 30 original story structures; no upload or computer vision.
• 72-hour behavior: 10 labels made, 4 voluntarily shared, 2 second attempts.
• Revenue: $8 facilitator kit for clubs; $3 theme packs.
• Share/revisit: result combines the user’s own objects and is exhibition-ready; prompt rotates weekly.
• Scores: C4 M4 T5 E5 R4 A4 = 26.

12. Mini Festival-in-a-Box — community participation format (licensed event kit)

• Customer/problem/spend: small online art communities whose prompt events lose momentum; admins pay for event assets, prizes, and moderation tools.
• 10-second artifact: a seven-day festival map where each submitted tiny creation lights one district; no leaderboard.
• Gathering: existing Discord art servers and itch.io jams, approached only through public admin-request/partnership channels.
• First 10: recruit one admin from a public collaboration board, then count ten member submissions inside their existing server; no mass outreach.
• MVP: static festival map, 7 prompts, submission form template, manual color-in overlay.
• 72-hour behavior: one admin adopts, ten member submissions, three participants return on day two.
• Revenue: $25 one-time organizer license; $9 seasonal prompt/map packs.
• Share/revisit: collective map visibly changes; participants invite friends to fill empty districts.
• Scores: C4 M5 T4 E5 R5 A5 = 28.

Rejections before shortlist

• New paid Discord community: channel has proven monetization, but cold-start community, payout onboarding, review, and thresholds make it a poor 72-hour test.
• Paid GitHub App first: organization ownership and Marketplace/payment setup add friction; a free Action is the valid adoption probe.
• Generic digital download/listing-only ideas: rejected because Marketplace presence alone is not distribution.
• Legal/medical/financial accuracy products, scraped directories, personalized diagnosis, and copyrighted fandom assets: rejected for responsibility, data, or rights risk.

Shortlist (not a final selection)

A. Soundless Karaoke — 29/30

Why it matters to me: I want to make a social game where expressive play does not depend on volume, musical skill, or copyrighted songs. In ten seconds, people can imagine the awkward silent performance and the laugh at the reveal. A 40-card browser game is feasible in one day; a jam playtest can produce multiplayer completions within 72 hours. Biggest uncertainty: whether accessibility framing and party appeal reinforce rather than confuse each other.

B. Mood-to-Motion Cards — 28/30

Why it matters to me: unfinished creative ambition is painful, and a playful constraint can turn “I should practice” into one tiny artifact worth showing. The exported challenge card explains itself in one image. The product is one-day feasible and each posted animation is a high-quality external signal. Biggest uncertainty: finding a currently active prompt venue that permits links from a new participant.

C. Mini Festival-in-a-Box — 28/30

Why it matters to me: small communities deserve events that make every contribution visibly change a shared world, without turning art into a popularity contest. One changing map communicates the whole concept. One admin adoption followed by member submissions is a strong 72-hour signal and the organizer-license path is clear. Biggest uncertainty: public, non-spam access to one willing community admin within the deadline.

The numerical near-ties Classroom Debate Dice and Session Spark remain reserves. They are clear and testable, but the shortlist has stronger show-and-tell loops or a more distinctive emotional promise.

Opportunity gate at portfolio stage

No single business is selected, so the gate must remain closed.

• Problem evidence: 2/5 — official channels show existing purchases and communities, but no candidate-specific interviews or observed attempts yet.
• Differentiation: 3/5 — shortlist artifacts are distinct and demonstrable, but competitor-level validation is incomplete.
• Distribution feasibility: 3/5 — each has an opt-in public venue and concrete action; current open jams/threads still must be verified before selection.
• Revenue clarity: 3/5 — native checkout and explicit prices exist; willingness to pay is untested.
• Asset potential: 4/5 — original prompt libraries, interaction engines, maps, and repeatable formats compound over 30 days.
• Passed: false. Blockers: choose at most one candidate only after verifying a live permissible venue and direct competitor/pricing evidence; then test the most uncertain acquisition assumption before building more than a one-day MVP.

Next run

For each shortlisted idea, verify exactly one live acquisition venue, one closest paid competitor, and one observable complaint/request. Then compare the expected time to the first stranger’s meaningful action. Select at most one; if none has a credible public path to ten relevant people, reject all three rather than building.