Cabal (Megadrive / Genesis)

An unofficial fan port of the 1988 arcade shooting game Cabal (TAD Corporation) to the Sega Mega Drive / Genesis.

This is not a remake or a reimagining. The Mega Drive runs the arcade game's own 68000 program, unchanged. Only the display, the sound hardware and the controls were rewritten for the console. On every test run, including a full game from the first level to the ending, the game plays exactly like the arcade, frame by frame: same enemies, same patterns, same scoring.

This is a beta. It has been tested in emulators but not yet on real hardware. Feedback is very welcome!

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Features

• Made with Claude Opus 5.5
• The original arcade game logic, running as-is on the Mega Drive's 68000
• Arcade resolution (256 × 224) with converted colours
• The original sound program (music, sound effects and priorities) running on the Mega Drive's Z80 and FM chip
• Voices and explosions (ADPCM) played through the console's DAC
• Simultaneous 2-player mode (player 2 on pad 2)
• Free play: no coins to insert
• Options menu replacing the arcade DIP switches
• Runs at 60 Hz and 50 Hz, all regions (Japan, USA, Europe)

Options menu

The menu appears at power-on, before the game.

• LIVES: 2, 3, 5, 121
• DIFFICULTY: EASY, NORMAL, HARD, VERY HARD
• BONUS LIFE: 150K +500K, 200K +600K, 300K +700K, 300K ONLY
• DEMO SOUND: ON, OFF
• PAD 1 / PAD 2, BUTTON A, B, C: FIRE, GRENADE, BUTTON 3

Defaults are in bold. Up/Down selects a line, Left/Right (or A, B, C) changes the value, START begins the game. Settings are not saved when the console is switched off.

Controls

A 3-button or 6-button pad works (only A, B, C and START are used).

• D-pad: move the soldier and the crosshair
• B: fire
• C: grenade
• A: arcade button 3
• START: start, or continue after a game over

Differences from the arcade

• Speed. The Mega Drive's CPU is slower than the arcade board's (7.67 MHz vs 10 MHz) and it also has to convert the picture. When the screen gets busy the game slows down: about 10% on average, up to 24% in the heaviest scenes. The game itself stays identical, only the pace changes.
• Sound. The music uses the original notes, timing and priorities, played on the Mega Drive FM chip, so the tone is slightly different. Voices and explosions are quieter relative to the music than in the arcade, because the console's 8-bit DAC cannot go louder.
• Display. Static scenery made of sprites (walls, barrels, houses…) is drawn on a background plane to stay within the console's sprite limit. Enemies still pass in front of or behind it as in the arcade.
• At the start of each level the screen stays black for about half a second while this scenery is prepared.
• When there are a great many sprites on screen, some may flicker.

How to play

• Load cabal_md.bin (2 MB, no save) in a Mega Drive / Genesis emulator, or on a flash cartridge.
• Tested in MAME (genesis driver) and RetroBat.
• Not yet tested on a real console. If you try it on real hardware, please tell me how it goes!

Known issues

• Slowdown in busy scenes (see above).
• Possible sprite flicker with very crowded screens.
• Not yet confirmed on real hardware.

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Cabal is © 1988 TAD Corporation. This is a non-commercial fan project, not affiliated with or endorsed by the rights holders.