Frogbull Presses On With Metal Gear Solid Saturn Port

Saturn homebrew developer Frogubll, or “Frogbullsh*t” as some may affectionately say, posted a massive update to the Metal Gear Solid porting project. A video on the dev’s YouTube channel posted in September shows incredible progress with its development.

We asked Frogbull about how this incredible progress came together. Perhaps the one of the biggest updates is completely abandoning the Sega Graphics Library tooling and coding from well-known Saturn homebrew dev XL2. Another major change makes use of a new open-source project.

“The biggest change is without doubt the use of mgs_reversing (the FoxDie Team’s decompilation project of MGS1), which has brought this much closer to a genuine port.” Frogbull said.

“That came at a cost,” the homebrew dev added. “I had to restart most of my previous work and redo all the assets and levels. I kept my original conversion methods, but very little else survived. Mentally, that was a tough overhaul.”

It should be noted that decompilation project does not appear to credit Claude or any other such AI tool on its GitHub page. Likewise, Frogbull does not mention use of any AI tooling, elaborating on how so much more of the first Metal Gear Solid game is running on Saturn hardware.

“Using the original PS1 physics engine makes a huge difference, with authentic timing, movement speeds, collisions, and features like dragging unconscious enemies,” Frogbull told me. “I had to adapt the rendering to the Saturn of course. Yaul is f****** great, but provides less easy features than the SGL, on the good point it offer more flexibility and doesn’t cost as much RAM [which] is essential for fitting everything MGS needs.”

“Both VDPs are used, with the entire UI now on VDP2,” Frogbull explained. “This frees up precious space in VDP1’s 512 KB of RAM and allows proper transparency, especially for the radar, which now looks very close to the PS1 version (very happy with the Radar, so iconic to MGS) and VDP2 also handles the water surface in the docks and will be used for other special tricks, though that still needs work.”

Though much of the motherboard is firing off here, use of the second SH-2 processor is still in the works.

“The slave SH-2 is barely used for now,” Frobull said. “I want to divide tasks carefully so both CPUs can work without constantly waiting on each other. The radar might seem like an obvious candidate, but it depends on game state managed by the master SH-2. Untangling those dependencies will be tricky, but the potential performance gains are worth it.”

This timeless classic from Hideo Kojima does much more than tell a compelling interactive story. It apparently demands a large amount of power from fifth-generation console hardware. Getting the unique power of the Sega Saturn to pump this out makes it one of the more intense projects in Frogbull’s workshop.

“MGS on Saturn is among my most ambitious projects, and one of its biggest challenges is … audio,” Frogbull said. “Visuals sadly always get most of the attention (damn human brain wired for that :D), but sound in MGS … it’s a very tough one. The PS1’s SPU has a major advantage: hardware ADPCM decoding. Both machines have 512 KB of sound RAM, but compressed samples make that space go much further on PS1 (ratio of 4:1). Matching that on Saturn while handling music, effects, and voices will be very difficult.”

“For Codec conversations, I’m considering ADX, as used in Burning Rangers, or another compression format,” Frogbull added. “Software decoding costs CPU time, but Codec scenes should leave enough room for it. Keeping everything running smoothly during gameplay, within the sound RAM budget, is another story.”

Though it is a mentally laborious task, it seems Frogbull still manages to find joy in pushing this video game into the so-called benchmark of engineering excellence.

“That’s the fun of optimization,” Frogbull told me. “Torturing your brain over a machine as quirky as our good old Saturn.”