Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Little Crane World Editor
World Editor for the game 'the little crane that could'
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 3.1
95 ratings · Below Average
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included14 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Little Crane World Editor: map the core Productivity workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Enhance element variety and provide more customization features.
Assumption to check: Limited element selection and customization options.
Validate with people who use this workflow before building.
Hypothesis 2
Implement a guided tutorial for first-time users.
Assumption to check: Complex user interface for new users.
Validate with people who use this workflow before building.
Hypothesis 3
Optimize rendering for larger canvases.
Assumption to check: Performance issues with larger landscapes.
Validate with people who use this workflow before building.
Hypothesis 4
Introduce a community gallery for users to share and discover creations.
Assumption to check: Lack of community sharing features.
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
World Editor for the game 'the little crane that could'. With this World Editor, you can make your own levels for that game. Currently discounted with 50% during the introduction of this new app. Get it now before the price goes up. The level designs are stored in iCloud. Users can share levels with friends. Note: Before buying, enable iCloud on your devices. Do not buy this World Editor if you do not want to, or can not enable iCloud for your devices. [see below] Note: To play the levels created, you will need to download the (free) game separately. The world editor is compatible with the game version 4.3 and later. Support for retina iPhone and retina iPad. iCloud storage for level designs. Online video tutorial on the use of the World Editor. To check whether iCloud is properly enabled, please open the 'Settings' app of your device, and go to the 'iCloud' tab. Then check that 'Documents & Data' is switched to 'ON'.
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Supabase
Redux
React Navigation
react-native-reanimated
BUILD KIT DIFFICULTY
Advanced
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
