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The retro YouTuber/game developer Modern Vintage Gamer has put out a new video about his challenge to the homebrew community to get DOOM running on the Neo Geo.
And it seems he's now ready to admit defeat, admitting, "I was wrong," and that he now believes that a DOOM port may be possible on the platform after all.
This change of opinion is motivated by a bunch of exciting new projects that have appeared over the past five weeks since the original video went live, showcasing alternative techniques for building a DOOM-like experience on the platform — three of which MVG has decided to spotlight in an update to his 932k subscriber base.
“About a month ago, we made a video talking about the complexities of running a game such as DOOM on the Neo Geo," said MVG in the video's introduction. "This is because the Neo Geo does not have the concept of a frame buffer, meaning everything that you see on a screen on a Neo Geo is rendered as a sprite."
"I initially talked about the concept of a raycaster engine, which worked pretty well on the Neo Geo… But of course, a raycaster and a DOOM-style engine are not the same. A raycaster can only handle a grid, which is square blocks, which means everything has to be the same height and all the walls are at right angles. Doom, on the other hand, is a bit more complicated. You can have walls that are on any angle. Rooms at different floor heights. There are staircases, lifts, doors, sloped sightlines — nothing like this fits on a raycasting game."
As a result, members of the community have been stepping "up to the plate" to try and take things even further, and make an even more accurate recreation of the game, coming up with alternative ways of tackling the hardware issues, in porting DOOM.
In the new video, for instance, MVG shares a look at two projects that attempt to port DOOM 64KB, a 64KB version of DOOM for PC, to the Neo Geo.
This includes a port from DOOM 64kb's original author Frenkels, which includes "real BSP" (binary space partitioning), "real map geometry" that works by taking the real DOOM rendering code and squeezing it down small enough to fit on the Neo Geo, while using the Neo Geo's fixed/text layer as a tiny frame buffer. And another project from Sabino, who has built a microframebuffer from sprites instead of using the fixed or text layer to create a less blocky version, albeit at a performance cost.
This isn't the only project that has MVG excited, either, with the developer also highlighting a third project: Retro Port's DOOM Neo Geo, which opts for a completely different technique than the others. This still uses the sprite-based hardware without a frame buffer, but uses a new renderer called Vslice, which "takes all the good parts of the Raycaster approach and throws away all the bad stuff."
As MVG explains, “It keeps the hardware scaler to draw all the pixels, so there’s no frame buffer, and there’s no per-pixel CPU work, just like the raycaster. But instead of casting rays through the grid to decide what’s visible, it warps through an actual BSP tree... the data structure that builds out the map for you.”
As MVG clarifies, none of these ports is what you would consider "finished," and neither is going to come out "anytime soon," but it is still tremendous progress, regardless, and enough to have MVG admitting that DOOM is technically possible on the hardware, but it's just a matter of time.