mightyweenie

A reimplementation of Mutant League Hockey (Sega Genesis, Electronic Arts / Abalone, 1994) in Godot 4.7.1, built by reverse engineering the original in Ghidra using Opus 5.5.

This is a spite project I did partially to prove a point (that reverse engineering a Genesis game is now a trivial endeavour). In total, it took about three days to go from nothing but Ghidra, BlastEm/GPGX and the ROM to the state of this project as initially published to Github. As it stands now, most functions of the ROM have been uncovered and documented and all that's left are unfinished, unused features and code paths, debug functions and Genesis-specific video/audio routines.

Mightyweenie isn't a recompilation in the traditional sense, but built with GDScript in such a way that matches the original game's behaviour. Audio is handled through emulating FM synth using ymfm, PCM playback and mixing is handled natively by Godot.

New Features

• 3D rink view - switchable at any moment during play, with exactly the same gameplay as 2D. The rink is a 3D model textured live from the supplied ROM. Alternate views are available via F row keys, though they can cause some visual issues for the moment.
• 3D nets - The standard net and the Battle Net pull colour data and some texture information from the ROM too.
• 3D crowd - Fans are cut from the ROM's crowd art and seated on 3D stands. Missing front and back views, as well as mising pixel information, were drawn by hand and are merged on top of the ROM's graphical assets.
• Unlocked frame rate - The 3D view renders at any frame rate and blends smoothly between simulation steps. The game logic still runs at the original's rate.
• True translucency - In place of the Genesis shadow and highlight effects.
• Keyboard and gamepad support - Accessible using the new Options menu.
• Online multiplayer - up to 12 players on as many machines, every machine running the same game from the same inputs; encrypted, with a password if you like (see "Playing online" below).
• GAME TIMING - UNLOCKED, the new default, plays the game as on a stock Genesis, never slowed by load, with your player and the picture updated at TICKRATE (30 or 60 HZ; 20 to 240 HZ offline, experimental). ORIGINAL and APPROXIMATED keep the original's pace. UNLOCKED is recommended, it's very close to the original game's non-overclocked behaviour.
• Positional sound - the effects in stereo, placed by the camera in 2D and 3D and heard off screen too (POSITIONAL SOUND; ORIGINAL keeps the original's).
• Local play for up to 12 - every player on a controller of their own, with character selection, captains and line-ups before a match; playoff runs can be saved and loaded.
• EXTENDED play - 2D EXTENDED and 3D EXTENDED cameras zoom to keep every player's character and the puck in the picture, with optional EXTENDED PENALTIES and EXTENDED CPU.
• CREATE-A-TEAM - teams of your own: city, name, logo and colours, and a coach with his own face and speeches.
• Replays - FULL GAME instant replays rewind over the whole match; matches and the attract demos can be saved and watched again from REPLAYS.
• Arena paint - blood and oil stay on the 3D ice, boards and glass all match, with detailed ice and reflections (VISUALS); REPLAY BLOOD shows the paint in replays too.
• A livelier arena - the crowd sways and cheers with the game, 3D benches, the match's opening in 3D, and a pool of new organ tunes.
• Widescreen - Supports arbitrary widescreen resolutions in 2D and 3D.

No ROM data shipped. All art, maps and data are read from your own ROM at runtime. Exported builds look for it next to the executable (or the AppImage), in the user data folder or at a --rom= path; when it is in none of those, a file dialog asks for it and the game keeps a copy in the user data folder.

For developers: you can browse the ROM's graphics in the Godot editor, and the simulation is checked step by step against recordings of the original.

Targets Linux and Windows. Further ports are welcome.

Playing online

START GAME, then ONLINE MULTIPLAYER. One player hosts, the others join; everyone needs the same build of the game and the same ROM (the game checks both).

• Hosting: HOST GAME, choose a PORT (42032 unless you change it) and a PASSWORD (or none), START SERVER. The lobby lists your addresses to share; COPY ADDRESS puts one on the clipboard. Local players join with any button on their controller and leave with Back. START GAME when everyone is in.
• Joining: JOIN GAME, type or paste the host's address (192.168.1.20, example.org, 203.0.113.5:42032, [2001:db8::5]:42032; the port is 42032 unless the host says otherwise) and the password, CONNECT TO SERVER. Passwords ignore case.
• The port (UDP): the host's machine must be reachable on its port over UDP. On a home network that means the router forwards UDP port 42032 to the hosting computer. The game asks the router to do it by itself (UPnP): the lobby says PORT OPEN when that worked and OPEN PORT 42032 ON YOUR ROUTER when it didn't - then add the forwarding in the router's settings (UDP, the port, the hosting computer's local address). Players on the same local network can join with the host's local address and need no forwarding.
• Firewalls: allow the game to receive on its UDP port on the hosting computer (Windows asks the first time you start a server: allow it). Joining needs nothing.
• IPv6: the host listens on IPv4 and IPv6 at once. Over IPv6 there is usually nothing to forward, but the router's or the computer's firewall may still have to let UDP 42032 in.
• Passwords and encryption: every connection is encrypted. The password itself never crosses the network.
• the game remembers each host's key the first time you join it: If it changes, the game asks before going on. That is expected when the host plays on another computer or has reinstalled the game (or deleted its saved data); if not, someone may be in the middle - ask the host, and use a password.
• Dropping out: if your connection or the game drops, ONLINE MULTIPLAYER offers REJOIN while the match goes on: you get your players back from the next face off. The CPU plays for you meanwhile, and for any player who lags or leaves.
• The host's upload speed: hosting takes about 80 kbit/s of upload for each machine that joins, so about 1 Mbit/s for a full lobby of 11. On a slower line the host sends half as often by itself: a full lobby still plays on about 0.7 Mbit/s and gets laggy below that.
• A slow or lossy connection makes your game wait now and then; very bad ones (a fifth of the traffic lost) can drop you, and REJOIN brings you back.

Building

tools/setup/fetch_tools.sh && tools/setup/setup_python.sh
tools/bin/setup-rom         # your ROM into the Godot project (game/rom/mlh.gen)
tools/bin/build-audio       # the audio extension (needs g++ and make)
tools/bin/godot-test        # Godot unit tests (GUT, headless)
tools/bin/harness-test      # reference-emulator tests (pytest)
tools/bin/godot-editor      # open the editor (desktop)
tools/bin/compare compare/scripts/coop_start.mwi   # original vs ours, first difference
tools/bin/export-linux      # packages in out/builds/ (also tools/bin/export-windows)

Licences

The project's code is under the BSD 3-Clause License (LICENSE). It covers this project's own code only; the game's data is not included. Vendored: GUT (MIT). The audio extension's third-party code (ymfm, godot-cpp) is listed in game/addons/mw_audio/THIRD_PARTY_NOTICES.txt. The input glyphs are "Virtual key codes tileset" by YellowAfterlife (CC0) and "Pixel Button Prompt" by FrankTheApe (free for commercial use); see game/assets/glyphs/CREDITS.md. Tools fetched at setup keep their own licences; emulators are used for observation only and are not linked into the game.

Mutant League Hockey is a trademark of its owners. This is an unofficial fan project, not affiliated with or endorsed by Electronic Arts or Sega.