Fxgl Project Starter

FXGL Project Starter

Purpose

Use this skill when the goal is not just "write some FXGL code", but to start a project correctly:

1. discover what the user actually wants to build
2. turn that into a reviewable project specification
3. scaffold the project only after the documentation is agreed
4. keep docs, implementation, and tests synchronized from the first commit

This is a workflow/orchestration skill. It should usually invoke more specialized skills after the starter specification is complete.

Execution Modes

This skill must support two modes.

1. Interactive Socratic Mode

Ask one focused question at a time. Use the bounded question flow from references/question-flow.md.

2. Default Mode

If no interactive user is available, proceed with conservative defaults:

• Java
• Maven
• 2D game
• local single-player
• desktop target
• no networking
• no save/load unless explicitly requested
• no AI/ML features unless explicitly requested

Never block indefinitely waiting for answers if the runtime is non-interactive.

Bounded Socratic Rule

Do not ask unbounded exploratory questions forever. Ask just enough to unlock project decisions, then move to documentation.

Minimum topics to resolve:

1. game/app type
2. target platform
3. 2D or 3D
4. input model
5. progression / save expectations
6. technical baseline (Java, build tool, modules)

If the answers remain partial after the bounded flow, document the assumptions and proceed.

Docs-First Checkpoint

Before generating any Java source files, verify that the starter specification exists and is populated. The minimum documentation set is:

• docs/project-brief.md
• docs/use-cases/core-use-cases.md
• docs/architecture/arc42-lite.md
• at least one ADR under docs/architecture/adr/

If these files do not exist yet, create them first.

Required Documentation Outputs

Project Brief

A short, easy-to-scan summary for humans:

• one-paragraph game / app summary
• core player loop or primary workflow
• success criteria
• top risks
• current scope and out-of-scope items

ADRs

Use ADRs only for important, hard-to-reverse decisions:

• 2D vs 3D
• Maven vs Gradle
• single scene vs room/level-based structure
• physics-heavy vs non-physics design
• multiplayer or not

Use the template in references/adr-template.md.

arc42-lite

Use a practical starter subset, not a bloated architecture book. Follow references/arc42-lite-outline.md.

Include:

1. goals and scope
2. constraints
3. context
4. solution strategy
5. building blocks
6. runtime flow
7. risks / technical debt

Mermaid Use-Case Diagrams

At minimum, create:

• actor + main use cases
• core runtime flow
• one system decomposition diagram if the project already has clear subsystems

Suggested Output Layout in the Created Project

docs/
├── project-brief.md
├── implementation-plan.md
├── use-cases/
│   └── core-use-cases.md
└── architecture/
    ├── arc42-lite.md
    └── adr/
        ├── 0001-project-shape.md
        └── 0002-build-and-runtime-baseline.md

Project Initialization Step

After the starter specification is approved:

1. choose Java vs Kotlin
2. choose Maven vs Gradle
3. choose package name
4. choose app name and main class
5. choose minimal FXGL feature set
6. create the project skeleton
7. add the initial GameApplication scaffold

For lifecycle hook implementation, load fxgl-game-lifecycle.

For game-specific behavior, load the chosen game-type skill(s).

Minimal Scaffold Expectations

The initialized project should include:

• build file (pom.xml or build.gradle)
• main app class extending GameApplication
• initial initSettings()
• placeholder lifecycle hooks as needed
• src/main/resources/assets/ structure
• docs/ starter specification files
• src/test/ with initial automated test scaffold

Testing Rule

"Every step is tested" means:

Tier 1 — pure unit tests

Use standard JUnit tests for:

• rules
• calculations
• save data transformations
• progression logic
• non-FXGL domain models

Tier 2 — FX / JavaFX tests

Use @ExtendWith(RunWithFX.class) for:

• JavaFX node creation
• FXGL texture / UI related helpers
• logic that requires JavaFX initialization

Tier 3 — launch smoke tests

Only when the environment supports it, add an optional FXGL application boot test.

Do not pretend every environment can run a full display-backed game launch.

See references/test-strategy.md.

Synchronization Rule

For each implemented project step:

1. update the relevant documentation first
2. implement code
3. add or update automated tests
4. verify docs still describe the actual behavior

If implementation changes invalidate the current ADR or architecture summary, update the docs in the same change set.

Recommended Skill Composition

This skill is the entry point. After the project brief is approved, combine it with:

• fxgl-game-lifecycle for application bootstrap
• the selected game-type skill such as fxgl-platformer, fxgl-topdown, fxgl-rpg, etc.
• fxgl-ui-scenes, fxgl-save-load, fxgl-level-assets, or other subsystem skills as needed

Gotchas

• Socratic questioning must be bounded — endless discovery loops are not progress.
• Do not generate code before the minimum docs exist — this skill is explicitly docs-first.
• Full arc42 is too heavy at project start — use the practical arc42-lite subset, then expand only if the project truly needs it.
• ADRs are for major decisions only — do not create one ADR per tiny implementation choice.
• Automated tests must match the environment — pure unit tests are mandatory; display-backed launch tests may need to be gated.
• This skill should not replace specialized FXGL skills — it selects and sequences them.