Skin Checker for osu!: Ensure Compatibility & Polish Your Skin

Skin Checker for osu!: Automated Skin Validation for Mappers

What it is
A utility that automatically inspects osu! skin folders and beatmap previews to find visual and functional issues that affect gameplay, readability, or aesthetic consistency.

Who it’s for

• Beatmap mappers preparing maps for release
• Skin creators ensuring compatibility with gameplay elements
• Tournament staff / moderators checking submitted skins

Key checks performed

• Missing assets: Detects absent required images (hitcircle, approach circle, cursor, etc.).
• Incorrect file names: Flags files that don’t match osu!’s expected filenames or extensions.
• Dimension & format issues: Verifies image sizes, aspect ratios, and supported formats (PNG, JPG, etc.).
• Transparency problems: Finds unwanted opaque/transparent areas that break visuals (e.g., non-anti-aliased edges).
• Color & contrast warnings: Highlights low-contrast HUD elements or hitobjects that may be indistinguishable against common backgrounds.
• Animation/frame sequence errors: Checks sprite sheets and frame order for hitcircles, numbers, and other animated elements.
• Scaling & alignment: Simulates common resolutions to spot misaligned or improperly scaled assets.
• Performance concerns: Flags overly large files or unoptimized images that increase load times.
• Inconsistent art style: Heuristic checks for mismatched palettes or icon styles across assets.
• Compatibility hints: Notes osu! game-version assumptions (legacy vs. modern skin elements) and potential deprecated filenames.

Outputs

• Human-readable report listing issues by severity (Error / Warning / Info).
• Suggested fixes for each issue (rename, resize, re-export, replace).
• Preview thumbnails showing problem areas.
• Optional auto-fix for simple issues (rename files, resize/resample images).
• Exportable checklist for release notes or mapper submission.

How it works (brief)

• Scans a skin folder and optionally specific beatmaps.
• Compares present files against a ruleset of required and optional assets.
• Runs image analysis (dimensions, alpha channel, color contrast) and lightweight rendering previews.
• Applies rules that reflect osu!’s skinning spec and common community best practices.

Integration & usage

• Standalone GUI application with drag-and-drop skin scanning.
• Command-line mode for CI or pre-release checks.
• Plugin for mapping tools (e.g., editor extensions) to run checks during mapping.
• Batch mode to validate multiple skins or map packs.

Benefits

• Reduces release issues and player confusion.
• Speeds up QA for mappers and skin authors.
• Improves accessibility by catching contrast/readability problems.
• Helps maintain a consistent visual experience across maps.

Limitations

• Heuristic style checks can produce false positives for intentionally experimental skins.
• Automated contrast checks may not reflect all player display conditions (monitor, brightness).
• May not catch logic/gameplay bugs unrelated to skin assets.

If you want, I can:

• Draft a CLI usage spec, GUI mockup, or ruleset for the validator.
• Create sample report output for a typical skin.