How to Make a Nintendo 64 Game in 2026

— Tuesday, August 4th 2026 Two years ago, I was Porting my JavaScript Game Engine to C for No Reason. I have since found a reason: making a new N64 game! The result is Xibalba 64 – a Wolfenstein 3D-like FPS. Modretro agreed to publish the game as a physical launch title for their M64 (a modern N64 clone), complete with cartridge, packaging and manual! Xibalba 64 on Modretro.com This, to my knowledge, is only the second physical release of any new N64 game since the end of the console's original commercial life. The infamous Xeno Crisis by Bitmap Bureau – originally a new game for the Sega Mega Drive and subsequently released on many, many more consoles – came to the N64 in 2023. No other new games have been published for the N64 since Tony Hawk's Pro Skater 3 in 2002. The Engine Impact was a JavaScript game engine I developed back in 2010. It was tailored for 2D action games, handling tile sheets, background maps, sprites and collision detection. It's very simple, but still a sound foundation for whatever you want to throw at it. Two years ago I rewrote Impact in C. Why? I don't know. It was fun. This C port, high_impact, has a notion of a “platform backend”. The platform handles the low-level plumbing – opening a window, creating a drawing surface, reading input, etc. Out of the box, high_impact comes with two platform backends (SDL2 and Sokol), and you can compile your game for either one. This already enables high_impact games to run on many different devices. The rendering backend in high_impact is also modular. You can compile your game with a software renderer, OpenGL or Metal (for iOS/macOS). Support for new platform backends or rendering backends can be added without modifying any other part of the engine. A perfect starting point for an N64 game. N64 Hardware and Platform Library The N64 is a quirky beast. In addition to the 93 MHz MIPS CPU (big-endian!), it has two coprocessors for handling graphics, sound and more: “Reality Display Processor” (RDP) – a fixed-function graphics processor “Reality Signal Processor” (RSP) – a programmable vector processor Both of these live in the same physical package, commonly called the “Reality Coprocessor” (RCP). Image from the N64Brew Wiki For the first few years of the N64's life, Nintendo closely guarded access to the RSP. It was exclusively used by Nintendo's officially sanctioned platform library, “libultra”. Only later did Nintendo allow game studios to write custom “microcode” (actually just MIPS assembly) for the RSP. Keeping the hardware happy is no simple feat, and the instructions for the RDP are quirky and complicated. Programming your game on bare metal is pretty much out of the question. In recent years, Nintendo's official “libultra” has made its way onto the internet, but using it would risk a copyright lawsuit. Luckily, the N64 homebrew scene has picked up a lot of steam in the last few years and we have a very capable alternative now: Libdragon. Libdragon is basically SDL for the N64. It provides facilities for drawing sprites and triangles, sound output, controller input and much more. It took me only a few evenings to build a new platform backend for high_impact on top of libdragon. I tested this with Biolab Disaster. The game code remained unmodified; performance was meh, but I was using the N64 hardware in the most naive way possible. Dev Environment Libdragon provides the compilers and everything else that's necessary to build a ROM file for the N64. The installation instructions and all other documentation are comprehensive and well-written. The library comes with many examples to get you started. In general, it was a pleasure to work with Libdragon. Just a heads up: you probably want to use the preview branch as the “stable” trunk branch has hopelessly fallen behind. For testing, a good emulator is invaluable. For the longest time, N64 emulation was extremely inaccurate. Lackluster emulation of the RSP and RDP coprocessors, in particular, was the cause of most problems. Most emulators just emulated Nintendo's platform library, libultra. They emulated the intent to draw a triangle, not what the hardware would actually do. While inaccurate, this made emulation possible at all in the early days. Famously, UltraHLE (“Ultra High Level Emulator”) was released well within the lifetime of the N64 and caused a lot of headaches and subsequent lawsuits. These days the N64 core in Ares is much closer to the actual hardware – the RDP and RSP are fully emulated, including accurate timing for the RSP. The infamous slow memory bandwidth of the N64, however, can still only be tested on real hardware (which recently caused me some disappointment). So you need a real N64 and a cartridge that lets you play arbitrary .z64 ROM files. The open-source SummerCart64 is excellent and available from many different manufacturers. Be aware: some manufacturers (especially on AliExpress) cheap out on the components of the board. SummerCart64 has the usual SD card slot to store your ROMs, but what makes it great for development is its USB-C port: you can directly connect it to your PC and upload a ROM as part of your build process using sc64deployer. I ended up with the N64 next to my PC, connected via USB, and used a cheap $10 USB analog capture card to display its video output in a window on my desktop. On Linux, it took some fiddling with mpv to get low-latency output; here's the script I used. With this setup, iterating on real hardware was just a matter of compiling and pushing the N64 reset button. The Game I originally made Xibalba as a demo for my JavaScript game engine in 2014. WebGL was still the hot new thing back then; a 3D game in a browser was quite a novelty. The game was very short, featuring only a handful of levels, weapons and enemy types. In contrast, I wanted Xibalba 64 to be a real game, not just a demo. So I not only needed to port the game to C and high_impact, but also expand on it with more levels, more enemy types and more weapons. high_impact is a 2D game engine, but Xibalba 64 is clearly 3D. Well, not quite. Since the game has no elevation, it can be mostly treated as 2D. You could conceptually play Xibalba 64 from a 2D top-down perspective. Of course, that wouldn't be as exciting, but all the physics, movement and shooting would work the same way. In this regard, the game is very similar to Wolfenstein 3D. Many of high_impact's physics functions expect a vec2_t argument with .x and .y components. But for drawing, I absolutely needed a 3D position, so I came up with this definition for a vec3_t type and changed the entity_t type: typedef struct { float x, y; } vec2_t; typedef union { vec2_t xy; struct { float x, y, z; }; } vec3_t; typedef struct { // ... vec3_t pos; vec3_t vel; // ... } entity_t; Now, whenever I need to call a function that accepts a vec2_t, I can “convert” from vec3_t for free: trace_t res = trace(collision_map, entity->pos.xy, entity->vel.xy); Since the inner vec3_t struct is “anonymous”, I can still access all values directly; i.e., entity->pos.z works just fine. The initial port of the existing levels and enemy types went quite smoothly and was finished in about two weeks. I then spent another few months on extending the game and optimizing the renderer. Most of Libdragon's functions fit naturally into a new platform and rendering backend, though I had to change some other parts of high_impact to bypass its mixer (Libdragon has its own, accelerated by the RSP) and image loader. Throughout the whole process, I retained the ability to build the game with the SDL2 or Sokol backends. This was great for playtesting game logic and enemy behavior. To make levels, I also implemented a simple hot-reload mechanism triggered whenever a level file changed. The level editor, bundled with high_impact, is a single self-contained HTML file. I ended up extending it quite a bit to add better support for lightmaps, display actual sprites for entities (instead of just boxes), add descriptions for entity settings and provide other small features. The single source of truth is still the C source code – the level editor reads it and extracts the entity types and supported settings automatically. Since the level editor still works with JSON files, I built a small map compiler that reads the JSON and emits binary data. While loading JSON on the N64 is of course possible, it added some unnecessary ~100 ms of load time. So during the build process, each JSON level file is converted into a struct that essentially looks like this: typedef struct { uint16_t magic; uint16_t entities_len; uint16_t map_width; uint16_t map_height; struct { uint16_t type_id; uint16_t x; uint16_t y; uint16_t settings_len; struct { uint16_t setting_type; // such as "name", "target", "size", ... union { float16_t float_value; int16_t int_value; struct { int16_t string_len; char string_value; }; } value; } settings[settings_len]; } entities[entities_len]; uint16_t collision_map[map_width * map_height]; uint16_t floor_map[map_width * map_height]; uint16_t wall_map[map_width * map_height]; uint16_t ceiling_map[map_width * map_height]; uint16_t light_map[map_width * map_height]; } level_t; The level compiler writes those values in big-endian format for the N64 and little-endian format for x86 (SDL2, Sokol, WASM), so we can easily read everything on all platforms without byte swapping. Rendering Libdragon itself has a function for drawing triangles: rdpq_triangle() inserts a single triangle draw call into the RDP queue. While this works, what you really want to do is submit your draw calls to the RSP, have some custom microcode to perform transformations, lighting, depth calculations, etc., and then let the RSP instruct the RDP to ultimately draw the triangle. The intricacies of the RDP and RSP were still new to me, but luckily another outstanding open-source library, Tiny3D, handles all this and more with a simple-to-use API. Getting something on the