Yu-Gi-Oh! Life Counter (.NET 8 + .NET MAUI)

A cross-platform Yu-Gi-Oh! life points tracker built with .NET 8 and .NET MAUI (Windows + mobile).
This project is a faithful migration of an original Next.js / React (TSX) prototype, keeping the same UX and rules while adopting a clean, testable C# architecture.

⚠️ Disclaimer: This is a fan-made utility app. Yu-Gi-Oh! is a trademark of its respective owners. This project is not affiliated with or endorsed by Konami.

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Features (ported from the original TSX app)

Core duel flow

• 2 players with configurable starting Life Points (default: 8000)
• Tap to edit LP using a calculator-style input
• Game log with:
  • automatic history entries per change
  • Undo / Redo
  • Clear log
  • Export log to .txt (same format as the original)
• Reset duel (clears LP + history)

Calculator / expression parser

Supports the same shortcuts and behavior as the TSX version:

• Absolute: 8000 → set to 8000
• Relative: +1000, -800
• Multiplication: *2, *3
• Division: /2, /3
• Percentage shortcut: %2 (divide current LP by 2)
• Thousands suffix: 8k, +2k
• Result is floored and LP never goes below 0

Duel tools

• Timer (start/pause/reset)
• Dice roll (1–6)
• Coin flip (heads/tails)
• Phase tracker (Draw → Standby → Main 1 → Battle → Main 2 → End)
• Counters (spell counters, tokens, turns, custom)
• Notes (auto-saved locally)

Settings

• Starting LP presets (8000 / 4000 / 2000)
• Theme: Dark / Light / Auto (system)
• Haptic feedback (mobile)
• Sound effects (optional)
• Keep screen on (optional)
• “Clear all data” (local-only)

Local-first

• All data is stored locally on the device.
• No backend. No tracking.

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Migration notes (TSX → .NET MAUI)

The original app used:

• Next.js + React (TSX)
• Zustand + persistence (localStorage)
• UI built with a mobile-first layout and a battery-friendly dark theme

This MAUI version keeps the same functional rules, but changes the internals to be:

• strongly typed
• unit-testable
• cross-platform (Windows + Android/iOS)

Important adaptation for mobile performance

• The original TSX prototype did not enforce a strict history size.
• In this MAUI port we enforce a hard cap of 1000 log entries per duel to avoid memory/perf issues on mobile devices.

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Solution structure (Option A)

This repository follows a simple, clean separation of concerns:

• YugiohLifeCounter (MAUI UI)
  • Pages, Views, ViewModels (MVVM)
  • Dependency Injection setup
• YugiohLifeCounter.Application
  • Use-cases/services (orchestrates domain operations)
  • App-level abstractions (storage, vibration, sound, etc.)
• YugiohLifeCounter.Core
  • Domain models + pure logic (game engine, calculator, state transitions)
  • No MAUI dependencies
• YugiohLifeCounter.Core.Tests
  • Unit tests for the pure domain logic (xUnit)

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Tech stack

• .NET 8
• .NET MAUI
• MVVM pattern (CommunityToolkit.Mvvm)
• Dependency Injection (built-in .NET host)
• xUnit (tests)

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Prerequisites

Recommended (Windows dev)

• Visual Studio 2022 with workloads:
  • “.NET Multi-platform App UI development”
• .NET 8 SDK (recent patch recommended)
• Windows 10/11 SDK (10.0.19041+)

If you see MVVM Toolkit errors about Windows SDK references, update your .NET SDK / Visual Studio. (As a temporary workaround, you can pin WindowsSdkPackageVersion in the MAUI .csproj.)

CLI alternative

• Install MAUI workload:
  • dotnet workload install maui

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Getting started

Run on Windows (recommended for early development)

1. Open the solution in Visual Studio.
2. Set startup project: YugiohLifeCounter
3. Choose target: Windows Machine
4. Run (F5)

Run on Android

1. Install Android emulator (via Android Device Manager) or connect a device.
2. Select target: Android emulator/device
3. Run (F5)

Build from CLI (Windows)

dotnet restore
dotnet build ./src/YugiohLifeCounter/YugiohLifeCounter.csproj -f net8.0-windows10.0.19041.0

### Run tests

```bash
dotnet test

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Export log format (TXT)

The export matches the original behavior:

• Header with duel title
• Current LP per player
• Duel duration
• History ordered from first change to last change, including timestamp, change, resulting LP, and optional expression

Example:

Yu-Gi-Oh! Duel Log
===================

Player 1: 6500 LP
Player 2: 8000 LP
Duration: 3m 12s

History:
--------
1. [15:02:01] Player 1: -1500 → 6500 LP (-1500)

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Roadmap (high level)

• Finish 1:1 UI parity with the TSX prototype (layout, spacing, typography)

• Implement local persistence for:

  • game state + undo stack
  • notes
  • settings

• Optional: sound + haptics toggles wired per platform

• Optional: “keep screen on” wiring per platform

• Polish + packaging (Windows MSIX / Android APK/AAB)

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Contributing

• Keep domain logic inside Core (pure + testable)
• Keep UI logic inside MAUI project (ViewModels bind to services)
• Add tests for any domain rule changes (YugiohLifeCounter.Core.Tests)
• Prefer small commits with clear messages

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Credits

• Original functional reference: Next.js / React (TSX) prototype
• UI inspiration: mobile-first duel tracker design principles
• Built as a clean, testable port to .NET MAUI

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