Xevious — Sega Mega Drive / Genesis

A faithful Sega Mega Drive / Genesis port of Namco's arcade Xevious (1982).

It is a third target for the jotd666/xevious line-by-line 68000 transcode of the arcade game, alongside the existing Neo Geo and Amiga ports. The platform-agnostic game core is reused essentially unmodified; everything Mega Drive–specific lives in src/megadrive/ and assets/megadrive/.

▶ Download / play: https://sirvh.itch.io/xevious-genesis

Screenshots

About this port

• Same gameplay as the arcade — the code is the reverse-engineered original logic (including the pseudo-random number generation), running on real Mega Drive features: VDP planes A/B, hardware sprites, a Window-plane HUD, CRAM palettes and DMA.
• 4-channel PCM sound (music + SFX) through the SGDK PCM4 Z80 driver.
• 1P / 2P, attract mode, hi-score table, and high scores saved to battery SRAM.
• Runs on BlastEm, Genesis Plus GX, Kega Fusion and PicoDrive (NTSC, 60 Hz), and should run on real hardware.

Technical write-up (display mapping, the OSD layer, the sprite cache, sound): see readme_megadrive.md.

Controls (3-button pad)

Input	Action
D-pad	move
B	zapper (air targets)
A	blaster (bomb, ground targets)
C	insert coin
Start	start game / pause

Known limitation

The arcade hardware had far more sprite budget than the Mega Drive (80 sprites total, 20 per scanline, 320 sprite-pixels per line, and sprites at most 32px wide). Very busy scenes — notably the large Andor Genesis fortress surrounded by enemies — can flicker, like many commercial Mega Drive games. This is a hardware limit, not an emulation bug. The Amiga (AGA) port handles the same scene with wide hardware sprites (the Andor Genesis is a few 64px-wide sprites, plus the player ship) and draws the smaller enemies as blitter "BOBs"; the Mega Drive's narrower sprites make the same scene tighter.

Credits

• Namco — original Xevious (1982).
• Mark McDougall (tcdev) — reverse-engineering, the platform-agnostic 68000 core, and the Neo Geo target.
• Jean-François Fabre (jotd) — Amiga target; the repository this is forked from.
• Andrzej Dobrowolski (no9) — Amiga music · phx — ptplayer replay code · DanyPPC — Amiga icon.
• Paulo Manrique — this Sega Mega Drive / Genesis port.

The upstream README (Neo Geo / Amiga details and build instructions) is preserved as readme_upstream.md.

AI disclosure

The Mega Drive–specific layer of this port (src/megadrive/, assets/megadrive/ and the build scripts) was developed with the assistance of an AI coding assistant (Anthropic's Claude). The platform-agnostic game core, the original reverse-engineering, and the Amiga / Neo Geo work are by the upstream authors listed above.

Building

Requires the SGDK m68k-elf toolchain and Python 3 with Pillow. Short version:

py assets/megadrive/convert_graphics_md.py   # arcade gfx -> MD tiles / palettes
py assets/megadrive/convert_sounds_md.py     # WAVs -> 16 kHz PCM samples
py build_md.py                               # assemble + link -> bin/xevious_md-<ver>.bin

Full details (and the original Neo Geo / Amiga build steps) are in readme_megadrive.md and readme_upstream.md.

Legal

A non-commercial, fan-made port and a fork of jotd666/xevious. Xevious and all of its original graphics, sound and trademarks are property of Namco / Bandai Namco.