Hackers Show Neo Geo Doom Ports Aren’t Impossible
▼ Summary
– Modern Vintage Gamer previously stated Doom is functionally impossible on Neo Geo due to sprite-based hardware and no frame buffer.
– Two recent projects have made significant progress toward functional Doom ports on stock Neo Geo hardware.
– Both projects have significant graphical compromises that would have limited commercial viability in the 1990s.
– The Doom64KB project uses the console’s fix layer as a proto frame buffer, rendering at 28×32 resolution with 8×8 pixel tiles and 16 colors.
– A modified approach uses sprite memory to build a frame buffer at 80×56 resolution with 4×4 blocks, but at a noticeable cost to frame rate.
Last month, Modern Vintage Gamer (MVG) made a compelling case that running Doom on the Neo Geo was essentially impossible, given the console’s reliance on sprite-based rendering and its lack of a dedicated frame buffer. But telling a community of determined hackers that something can’t be done is practically an invitation to prove otherwise. Today, two separate projects are showing that a functional Doom port on stock Neo Geo hardware is far from a pipe dream, even if it comes with serious visual trade-offs.
Both efforts involve significant graphical compromises that would have made them tough to sell as a polished, commercial ’90s console release. MVG breaks down the technical limitations in a follow-up video, but the real story here is what clever, resourceful coding can squeeze from decades-old hardware.
A squint-and-it-looks-like-Doom experience
The first project, called Doom64KB, was created by coder FrenkelS. It adapts an earlier Doom engine originally designed to run on 16-bit PC processors like the 8088 and 286. On the Neo Geo, that engine repurposes the console’s fix layer,a portion of display memory typically reserved for menus and HUD overlays,to act as a primitive frame buffer.
Rendering to this fix layer allows the engine to animate Doom’s maps with surprisingly smooth motion, though the visuals are undeniably crude. The game displays chunky 8×8 pixel tiles at an effective resolution of just 28×32, with only 16 colors available. That color limitation means the iconic “light diminishing” effect, where walls grow darker with distance, is severely muted. A tweaked version of the same concept builds a frame buffer from the Neo Geo’s sprite memory instead, boosting the effective resolution to 80×56 by using smaller 4×4-pixel blocks. The trade-off is a noticeable drop in frame rate, though further optimization or overclocked hardware,like the upcoming Neo Geo AES+,could smooth things out.
(Source: Ars Technica)