Oxidizer

A mod loader for Kitten Space Agency, written in Rust. Mods can be written in Rust (cdylib) or as Rhai scripts.

KSA is a .NET 10 game, so the loader:

loads the game's own hostfxr.dll and starts its runtime with KSA.dll,
injects bridge/ (a small C# DLL plus Harmony), which hooks Program.OnFrame and Program.OnDrawUiViewports and gives mods reflection access to game objects,
loads the mods, then runs the game's Main.

Build

dotnet build bridge -c Release -o target/bridge
cargo build --release --workspace

Run

target/release/oxidizer.exe [--game "<KSA folder>"] [game args...]

On first run without --game, the loader creates oxidizer.toml next to the exe (game_path = '...'). It defaults to C:\Program Files\Ahwoo\Games\Kitten Space Agency.

Mods

A mod is a folder in Documents/My Games/Kitten Space Agency/mods/<id>/ whose mod.toml has a [oxidizer] section:

name = "my_mod"

[oxidizer]
dll = "my_mod.dll"      # Rust mod
script = "main.rhai"    # and/or Rhai script

Mods set enabled = false in KSA's manifest.toml are skipped. See examples/ for working mods. To install one, copy its folder into mods/; for a Rust mod, also copy in the built .dll.

Rust

The crate is a cdylib that depends on oxidizer_api:

use oxidizer_api::{Mod, Obj, imgui};
struct M;
impl Mod for M {
    fn init() -> Self { M }
    fn gui(&mut self, _dt: f64) {
        if imgui::begin("My mod") {
            let v = Obj::static_get("KSA.Program, KSA", "ControlledVehicle");
            imgui::text(&v.get("Id").to_string());
        }
        imgui::end();
    }
}
oxidizer_api::oxidizer_mod!(M);

Rhai

A script can define init(), frame(t, dt), gui(dt), and unload(). Keep state in this (an object map).

Area	Functions
Game objects	`static_get(type, member)`, `static_set(type, member, v)`, `static_call(type, method[, args])`, `obj.get(m)`, `obj.set(m, v)`, `obj.call(m[, args])`, `obj.float()`, `obj.is_null()`, `obj.len()`, `obj[i]`, `obj.to_string()`
Patching	`patch(type, method, "prefix"\|"postfix", "fn_name")`. The callback is `fn_name(instance, args)`; returning `false` from a prefix skips the original method.
ImGui	`begin(title)` / `end()`, `text`, `button`, `checkbox(label, v) -> v`, `slider(label, v, min, max) -> v`, `same_line`, `separator`, `header`
Logging	`print(...)`

Notes and limits

Members are looked up by name through reflection. Type names can be assembly-qualified ("KSA.Universe, KSA"), which works even before the game has loaded that type.
call picks the first overload with a matching argument count and converts arguments to the parameter types.
Patching uses the first overload of the method. Hooks receive __instance and __args, but not __result.
A Rhai script that throws an error is disabled, so the same error isn't logged every frame. Errors from reflection calls are logged once each.
ref struct members (for example ReadOnlySpan properties such as Program.VehiclesInFrame) can't be read through reflection.