SNES Star Fox now runs at a silky 60fps thanks to a new hack

A demo of the hacked, 60 fps version of Star Fox released this week (although this demo doesn’t get much above 30 fps, as indicated in the lower left corner).

If you were a Nintendo kid in the 90s, you were probably blown away by how Star Fox and its SuperFX chip can render full 3D worlds on 1993-era SNES hardware. However, if you go back to play the game today, you’ll likely be let down by the game’s choppy framerate, which maxes out at 20 fps.

Enter long Star Fox ROM cracker kandowontuwho is responsible for the feature-laden Star Fox Exploration Showcase cap. This week, kando a patch released which unlocks 30 or even 60 fps modes in a sequel Star Fox (or Star Fox 2em) ROM. The result is an extremely smooth experience that probably comes close to matching the rosy memories you have of the early 90s Star Fox than the original game ever could.

A problem of design

Attempts to accelerate Star Fox is nothing new in the hacking and emulation communities. For years players have overclocked SuperFX chips or run emulators at higher speeds to try to increase the game’s frame rate.

The SuperFX chip is just one of many cartridge collaborators that an SNES emulator must handle correctly.
Enlarge / The SuperFX chip is just one of many cartridge collaborators that an SNES emulator must handle correctly.

But while these methods make Star Fox run faster (and smoother), they also speed up the game’s internal logic to the same extent. This means enemy ships and your Arwing fly much faster than Nintendo intended, an effect that also throws the game’s excellent music out of sync with the on-screen auto-scrolling action. Tripling the game’s speed to get a 60fps experience makes it unplayably fast by all accounts.

The design and limitations of the original SuperFX chip make this a difficult problem to solve. In a game like Star Foxthe SuperFX chip can take two whole frame cycles to transfer its 3D images to the system’s video RAM (this is despite using only 75 percent of the available screen real estate). Add in computation time for game logic, enemy movement, etc., and the game renders a new frame at just one-third the SNES’s standard 60 fps rate.

“SuperFX games are kind of a special case,” emulator writer near (aka byuu) told Ars in 2019 while discussing an overclocking-focused update to them accuracy-focused emulator bsnes. “Since they tend not to run at 60 fps due to the demands of software that rasterizes entire screens on the SNES, the game logic is designed around the frame rates. So even if you speed up Star Foxthe game engine will now run too fast.”

Slow down your roll

To get around this problem, kando’s hack first reprograms the game to execute three frames of instructions (as measured in IRQ routines) in the space of one frame cycle (or two game cycles for 30 fps mode). But to prevent the game from accelerating itself, kando programmed his version to only recalculate the game logic (or “strats”) every third frame (or every other frame for 30 fps mode). “This slows the game back down to its ORIGINAL pace,” kando writes.

Unfortunately, kando notes that this hacked version of the game still need help from an overclocked SNES CPU and therefore, will not work on stock SNES hardware. Even in emulators set to run in overclocking mode, kando warn that, in 60 fps mode, “when there are some objects on the screen, the FPS becomes very variable between 30-60 fps (there also seems to be some problems with music speed in 60 fps playback).

Star Fox 2 looks smoother than ever

Limitations aside, it’s great to relive Star Fox‘s action-packed gameplay without the nausea-inducing framerates inherent in early 90s 3D graphics (or the nausea-inducing game speeds of previous framerate hacks). We play it together this weekend our slowdown-free, SA-1 enhanced copy of Grade III in an attempt to relive the best version of our childhood.

Leave a Comment