MCA Selector is a desktop application for editing Minecraft Java Edition world saves at the chunk and region level. It provides a graphical interface (JavaFX) and a command-line interface for operations such as selecting, exporting, deleting, importing, and modifying chunks and regions. The application reads and writes Minecraft Anvil (MCA) region files, including POI and entity data, and supports a wide range of Minecraft versions from 1.9 to the latest snapshots through version-specific mapping files and strategy pattern implementations (ChunkFilter, ChunkRenderer, ColorMapping). Architecturally, the application is a monolith with a clear separation of concerns: a UI layer (JavaFX dialogs, TileMap, custom components), a job system (JobHandler with priority queues and thread pools), a data layer (MCA file I/O, NBT parsing, caching via LevelDB), and a version abstraction layer. Key entry points include the Main class (launches GUI or CLI), the Window class (JavaFX stage), and the ParamExecutor (CLI dispatcher). External dependencies include a custom NBT library, Gson, fastutil, Log4j, Apache Commons CLI, Groovy scripting, LevelDB, LZ4, and RichTextFX. Data flows involve loading region files from disk, parsing chunk data (blocks, biomes, heightmaps, entities), applying user-defined filters and changes (including Groovy scripts), and saving modified chunks back to MCA files. The application also generates rendered tile images for the map view, with caching at multiple levels (memory, disk PNG, LevelDB). Overlays provide visual analysis of chunk properties (e.g., inhabited time, entity count) using hue-based coloring. While primarily an application, the repository includes a significant data component: version-specific block color mappings, heightmap definitions, and registry files (blocks, biomes, entities, structures) that are used for rendering and filtering. These mappings are generated by a separate tool within the repository that downloads Minecraft server jars and extracts data. This hybrid nature means the repo serves both as a tool and as a curated dataset for Minecraft world analysis.