Game & Watch

Game & Watch emulates Nintendo Game & Watch.

About this profile

Detail	Value
Type	libretro
Classification	Pure libretro
Source	https://github.com/libretro/gw-libretro
Upstream	http://www.madrigaldesign.it/sim/
Version	1.6.3, stated in src/libretro_version.c
Revision	libretro/gw-libretro@91d599b951e7
Profiled	2026-03-25
Profile	YAML, JSON
Cores	gw, gw_libretro
Systems	Nintendo Game & Watch

Technical 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 (src/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 (src/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.

No BIOS or firmware files required.

Profile data

Source 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: no

• system directory used: no

Next steps

• Get your files, for the setup you play on
• Every system, and the files each one needs
• When a game does not start

Data as of 4 November 2026.