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
Hafenskipper 2
Train to stop, turn & dock your ship with the second version of this realistic simulation app
$6.99 · In-app purchases
PRICE
$6.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
16 ratings · Top 15%
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.
Build your own version
Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included18 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 Hafenskipper 2: map the core Sports 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
Implement offline route caching and maps.
Assumption to check: Limited offline functionality for navigation
Validate with people who use this workflow before building.
Hypothesis 2
Simplify pricing structure and provide clear value.
Assumption to check: Subscription model can be confusing
Validate with people who use this workflow before building.
Hypothesis 3
Enhance data-fetching reliability and error handling.
Assumption to check: Occasional bugs in weather data updates
Validate with people who use this workflow before building.
Hypothesis 4
Streamline UI with better organization and spacing.
Assumption to check: User interface can feel cluttered
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
Train to stop, turn & dock your ship with the second version of this realistic simulation app. Maneuvering your ship in close quarters can be a challenge and must be trained well. Hafenskipper simulates harbor maneuvers under power and can help you to get a good understanding of the ship dynamics. Your Mission: - Maneuver the ships safely through the harbor - Dock at the pier and park in the slip - Choose one of 20 training levels or drive around freely - Prepare for the next driving lesson to get your boat driver's license - Practice docking maneuvers for your next trip Train with eight ships: - Motorboat with outboard engine - Motorboat with inboard shaft drive - Dinghy - Sailing yacht with engine - Large sailing yacht with engine - Small daysailer yacht with outboard engine - Motor yacht - Catamaran Features: + Realistic 3D physics simulation + 20 training levels, some with wind and mooring lines + Free running mode with optional wind and current simulation + Work with mooring lines in the free running mode + Free running bay mode with wind, mooring and anchoring + Detailed ship settings to adjust the behavior to a specific ship Improve your ship handling skills and get Hafenskipper 2 to start training!
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
react-navigation
expo-location
react-native-maps
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.
