emulator: "Game & Watch"
type: libretro
core_classification: pure_libretro
source: "https://github.com/libretro/gw-libretro"
profiled_date: "2026-03-21"
core_version: "Git"
display_name: "Handheld Electronic (GW)"
cores:
  - gw
systems:
  - handheld-electronic

notes: |
  gw-libretro runs Game & Watch simulators converted from MADrigal's Pascal
  source code via pas2lua. Each game is a self-contained .mgw archive (bzip2
  compressed tar v7) containing Lua scripts, sprites, and sound data.

  retro_get_system_info (libretro.c:187-194) sets valid_extensions to "mgw",
  need_fullpath to false, and block_extract to false. The core reads content
  entirely from the retro_game_info buffer passed by the frontend.

  retro_load_game (libretro.c:256-310) passes the content buffer to
  gwrom_init() which decompresses and parses the tar archive in memory.
  gwlua_create() then initializes the Lua VM from the archive entries.

  The core never calls RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY, never opens
  files from the filesystem, and has no firmware or BIOS dependencies.
  All game data is bundled in the .mgw content files available from
  libretro's buildbot (bot.libretro.com/assets/cores/HandheldElectronicGame/).

  No external BIOS or firmware files are needed.

files: []

analysis:
  content_format:
    extension: ".mgw"
    archive_type: "tar v7 + bzip2"
    decompression: "gwrom.c using bundled bzip2 library"
    source_ref: "gwrom/gwrom.h:21-27"
  game_engine:
    language: "Lua (bundled lua 5.3)"
    runtime: "gwlua (gwlua/)"
    rendering: "retroluxury (retroluxury/)"
    resolution: "128x128 base, variable via gwlua_set_fb/gwlua_zoom"
  filesystem_access: false
  system_directory_used: false