Friday the 13th The Game Modding

CS2SX — Write Nintendo Switch Homebrew in C# A C#-to-C transpiler that builds ready-to-run .nro files Have you ever wanted to write Switch homebrew but found C/C++ intimidating? CS2SX lets you write standard C# and compiles it directly to a Nintendo Switch .nro — no C knowledge required. You write this: public class MyApp : SwitchApp { private int _x = 640, _y = 360; private int _vx = 4, _vy = 3; public override void OnInit() => Graphics.Init(1280, 720); public override void OnFrame() { Graphics.FillScreen(Color.Black); _x += _vx; _y += _vy; if (_x 1260) _vx = -_vx; if (_y 700) _vy = -_vy; Graphics.FillCircle(_x, _y, 20, Color.RGB(0, 200, 255)); Graphics.DrawText(10, 10, "Press + to exit", Color.White, 1); if (Input.IsDown(NpadButton.Plus)) Environment.Exit(0); } } Run cs2sx build and put your .nro on your switch. How it works CS2SX is a transpiler — it reads your C# source using Roslyn (the official Microsoft compiler frontend), converts it to clean C, and then hands it off to DevkitPro's aarch64 GCC to produce the final .nro. The entire workflow is one command: cs2sx new MyApp # scaffold a new project cs2sx build MyApp.csproj # transpile → compile → package → .nro Copy the .nro to /switch/MyApp/ on your SD card and launch it from the Homebrew Menu. That's it. What C# features are supported? CS2SX supports a large and practical subset of C#: Full OOP — classes, inheritance, abstract/virtual/override, interfaces, generics Collections — List , Dictionary , Stack , Queue , HashSet LINQ — Where, Select, OrderBy, GroupBy, First, Sum, Any, All and 30+ more Strings — interpolation, Trim/Replace/Split/Join, StringBuilder Value types — struct, enum, Nullable , tuple returns Modern syntax — pattern matching, switch expressions, ??, ?. Extension methods, params[], ref/out parameters Graphics & Input CS2SX ships a built-in 2D framebuffer API: // Shapes, text, textures Graphics.FillRect(100, 100, 400, 200, Color.RGB(30, 30, 80)); Graphics.FillCircle(640, 360, 80, Color.Green); Graphics.FillTriangle(900, 150, 1100, 150, 1000, 300, Color.Orange); Graphics.DrawText(10, 10, $"Score: {_score}", Color.White, 2); Graphics.DrawTextShadow(10, 50, "Shadow text", Color.White, Color.Black, 2); // Load BMP textures from romfs (embedded in the .nro) Texture icon = Graphics.LoadTexture("romfs:/icon.bmp"); Graphics.DrawTextureCenteredScaled(icon, 0, 0, 1280, 720, 128, 128); // Buttons, analog sticks, touch screen if (Input.IsDown(NpadButton.A)) Jump(); if (Input.IsHeld(NpadButton.ZR)) Shoot(); StickPos stick = Input.GetStickLeft(); TouchState touch = Input.GetTouch(); if (touch.count > 0) Graphics.FillCircle(touch.X0, touch.Y0, 30, Color.Red); Project structure A CS2SX project is a standard .csproj you can open in Visual Studio or Rider — with full IntelliSense, autocomplete and error highlighting. MyApp/ ├── MyApp.csproj ← open in any IDE ├── cs2sx.json ← app name, author, icon ├── MyApp.cs ← your code ├── icon.jpg ← 256×256 app icon └── romfs/ ← assets embedded in .nro (BMPs, etc.) cs2sx.json: { "name": "MyApp", "author": "YourName", "version": "1.0.0", "icon": "icon.jpg" } Requirements - .NET 8 SDK - devkitA64 + libnx - Environment variable DEVKITPRO set to your DevkitPro install path //Install CS2SX via dotnet dotnet pack -c Release dotnet tool install --global --add-source ./bin/Release CS2SX Known limitations Being honest up front: One SwitchApp subclass per project (the main entry point) Interpolated strings ($"...") create stack buffers — safe in locals and output calls, but don't store them in fields No garbage collector — heap objects live until freed (the transpiler handles this automatically for most cases) async/await compiles synchronously No Reflection Source & Download CS2SX is fully open source under the MIT license. Download on Github: Here you can see the Github page and releases Example Projects: Here you can see example Projects build with CS2SX Issues, PRs and feature requests are welcome. If you build something with it, I'd love to see it posted here! Current version This version is stable and works with all Demo Projects. Enjoy v0.4.9.131_STABLE_NET8.0_x64 (Win) Built with Roslyn · DevkitPro · libnx

ROM Hack Friday the 13th The Game Modding

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