The Simpsons Game (the-simpsons-game-nx)

<h1 align=center>The Simpsons Game — Nintendo Switch port</h1> <p align="center"><img src="src/game/switch/icon.jpg" width="160" alt="The Simpsons Game"></p>

A native Nintendo Switch port of the Xbox 360 version of The Simpsons Game (2007).

It's not an emulator. The PowerPC code of the game's default.xex is statically recompiled to C++ with ReXGlue and compiled for the Switch, and the game is drawn by a native Vulkan renderer running on NVK (Mesa). It targets a locked 30 FPS.

the-simpsons-game-nx is built from TheSimpsonsGameRecomp, the recompilation of the game for PC, and takes its Switch layer and native renderer from project8-sw, the Switch port of Tony Hawk's Project 8, whose renderer adapts the one in nfsmw-nx by StevensND. See Credits.

[!NOTE] You need your own copy of the Xbox 360 game: a disc image (.iso) or the extracted disc with its default.xex. Supported: the USA retail disc (default.xex SHA-256 71d99dad…a82a231, title ID 45410809). The program is compiled from that exact executable, so other releases do not run.

How to install

1. Open the installer page: https://r-drg.github.io/the-simpsons-game-nx-installer/
2. Choose your format (Disc image (.iso) or Game folder, the folder with default.xex and the disc's folders) and press Create the-simpsons-game-nx.zip. Everything runs in your browser and the game files never leave your computer: the page checks your copy, downloads the build and puts the two together.
3. Extract the downloaded zip into sdmc:/switch/.

Your folder should look like this:

/switch/the_simpsons_game/
  the_simpsons_game.nro
  simpsons.toml             (settings)
  LICENSES.txt              (licences of the software in the NRO)
  game/                     (the files of your disc: default.xex, audiostreams, frontend, movies, ...)

The game creates simpsons/ (saves and caches) and logs/ next to the NRO the first time it runs.

Launch it in title takeover mode: hold R while starting any installed game to open the Homebrew Menu, then start The Simpsons Game. A forwarder should also work if you set it to a 39-bit address space. Applet mode (from the Album) gives homebrew much less memory and is not supported.

[!IMPORTANT] Clocks. The port was tested with sys-clk at CPU 1785 MHz and GPU 768 MHz in handheld mode, and that is what 30 FPS needs. At stock handheld clocks (CPU 1020, GPU 307) the game drops to about 19 FPS. Don't change sys-clk while the game runs, and leave switch_gpu_mhz at 0 in simpsons.toml when sys-clk is installed: both setting clocks at once crashes the console.

[!NOTE] Updating: open the installer page again and press Create the-simpsons-game-nx-update.zip. It only contains the NRO, simpsons.toml and LICENSES.txt, so there is no need to copy the game files again: extract it over your existing folder. It replaces simpsons.toml; note any setting you changed first.

Controls

Each Switch button acts as the Xbox 360 button with the same letter, so the letter in the on-screen prompts is the button to press.

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Switch	Xbox 360
A / B / X / Y	A / B / X / Y
ZR / ZL	RT / LT
R / L	RB / LB
+	Start
−	Back
Sticks / D-pad	Sticks / D-pad

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To use the face buttons by position instead, as on an Xbox pad (B acts as A, A as B, Y as X and X as Y), add input_xbox_layout = true to simpsons.toml.

Performance

Tested on a Switch in handheld mode at CPU 1785 MHz and GPU 768 MHz (set by sys-clk). Menus, cutscenes and normal play hold a locked 30 FPS. Scenes with many particles at once (Homer's burp, blowing things up) can drop briefly to 26–28 FPS: at that point the limit is the game's own CPU threads, not the renderer. Docked mode and stock clocks were not measured for this release.

The port caps the game at 30 FPS and spaces the frames evenly (gameplay_frame_rate, menu_frame_rate, nx_min_frame_vblanks in simpsons.toml). In busy areas such as the Springfield hub, where a frame takes about as long as 30 FPS allows, the game used to give a frame that was already late up to 16.7 ms more of background streaming work, which turned it into a 50 ms frame; since 1.0.1 a late frame gives it at most 2 ms (late_frame_task_ms).

Known issues

• A short hitch can happen the first time a new effect appears, while its pipeline is compiled.
• Heavy particle scenes can dip to 26–28 FPS.

More detail is in docs/known-issues.md.

How it works

• The game's code is translated, not emulated. ReXGlue translates every function of default.xex to C++, which is then compiled for the Switch, and gives the game what it expects from an Xbox 360: its system, files, audio and controllers. The Horizon (Switch) layer of the SDK, adapted from project8-sw, is in patches/rexglue-sdk/.
• Its own renderer. The port reads the commands the game sends to the GPU and draws the same frame with Vulkan: render targets are plain images, resolves are image copies, shaders are translated once and cached, textures are untiled on worker threads. Vertex data is copied only for the range each draw reads, worked out from the index range and the vertex shader. The game's four costliest full-screen effects use the PC port's hand-written replacement shaders (tools/native-renderer/native_shaders/), compiled into the NRO.
• Cutscenes decoded natively. The story cutscenes are VP6 movies. The game's own VP6 decoder, recompiled, took a whole core and could not keep up, so the picture fell behind the sound. FFmpeg's VP6 decoder decodes the same packets into the same buffers instead (src/game/src/movie_decoder.cpp, setting movie_decoder).
• Its own graphics driver. Vulkan runs on NVK, from the Mesa project, through mesa-switch, with project8-sw's changes in patches/mesa-switch/.

Build

devkitA64 and libnx from devkitPro, CMake, Ninja, Docker, TheSimpsonsGameRecomp (for its ReXGlue SDK) with patches/rexglue-sdk/, the Vulkan driver built from mesa-switch with patches/mesa-switch/, and your own copy of the game for the code generator. The whole process is in docs/building.md.

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Folder	Contents
src/game/	The game: hooks, frame pacing, native renderer (src/native/), Switch entry point, CMake project, code generator configuration
patches/rexglue-sdk/	The SDK changes: Horizon runtime, memory, input, audio, crash handling, GPU, in apply order (series)
patches/mesa-switch/	The graphics driver changes and its build script
release/	The settings file that goes into the package
tools/	Toolchain files, the replacement shaders, the notice generator and the release check
docs/	Documentation

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Credits

• Electronic Arts and EA Redwood Shores — creators of The Simpsons Game. This is an unofficial, fan-made port with no affiliation.
• TheSimpsonsGameRecomp and its contributors — the recompilation project this port is built from: the code generator configuration, the game's hooks, frame pacing and the replacement shaders.
• project8-sw — the Switch runtime, the native renderer and the driver patches this port reuses.
• StevensND — nfsmw-nx, whose native renderer src/game/src/native/ adapts (GPL-3.0) and whose Mesa changes patches/mesa-switch/0002 takes (MIT); and nfsmw-nx-installer, which the installer page is adapted from.
• Tom Clay — the ReXGlue SDK, built on the work of the Xenia team.
• danfromtico and NaGaa95 — mesa-switch: Mesa, NVK and NAK on Horizon. And the Mesa developers.
• devkitPro and switchbrew — devkitA64 and libnx.
• The other libraries listed in THIRD_PARTY_NOTICES.md, with their licence texts in NOTICE.

Switch port by Rodrigo Ferreira.

Legal

No affiliation with Electronic Arts, 20th Television or Gracie Films. The Simpsons Game and its marks belong to their respective owners. This repository contains no assets and no program code from the original game: the translated code is generated from your own default.xex when you build. The released NRO is that translation compiled for the Switch; it holds no game assets and not the original executable, and it needs your own copy of the supported disc next to it, which the installer page puts there on your own computer. Users must provide their own legally obtained copy. The NRO's icon is the game's cover art (src/game/switch/icon.jpg), used only to identify the game in the Homebrew Menu. Running homebrew requires custom firmware, which violates Nintendo's terms of service and can get a console banned — your call.

Source code is provided under the GNU General Public License, version 3 (see LICENSE), the licence of TheSimpsonsGameRecomp and of the nfsmw-nx code it adapts. The driver changes in patches/mesa-switch/ are under Mesa's MIT licence.