may the flake do it's job

flake.nix

@@ -1,27 +1,118 @@
 {
+  # Build Pyo3 package
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
-    systems.url = "github:nix-systems/default";
-    fix-py.url = "github:GuillaumeDesforges/fix-python";
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    crane.url = "github:ipetkov/crane";
+    fenix = {
+      url = "github:nix-community/fenix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
-    { nixpkgs, fix-py, ... }:
-    let
-      eachSystem =
-        f:
-        nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed (system: f nixpkgs.legacyPackages.${system});
-    in
-    {
-      devShells = eachSystem (pkgs: {
-        default = pkgs.mkShell {
-          buildInputs = [
-            pkgs.cargo
-            pkgs.rustc
-            pkgs.stdenv.cc.cc.lib
-            fix-py.packages.${pkgs.system}.default
+    inputs:
+    inputs.flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import inputs.nixpkgs {
+          inherit system;
+          overlays = [ inputs.rust-overlay.overlays.default ];
+        };
+        lib = pkgs.lib;
+
+        python_version = pkgs.python313;
+        wheel_tail = "cp313-cp313-linux_x86_64"; # Change if python_version changes
+
+        # Get a custom rust toolchain
+        craneLib = (inputs.crane.mkLib pkgs).overrideToolchain (
+          p: inputs.fenix.packages.${system}.complete.toolchain
+        );
+
+        project_name = (craneLib.crateNameFromCargoToml { cargoToml = ./game/Cargo.toml; }).pname;
+        project_version = (craneLib.crateNameFromCargoToml { cargoToml = ./game/Cargo.toml; }).version;
+
+        crate_cfg = {
+          src =
+            let
+              fs = lib.fileset;
+            in
+            fs.toSource {
+              root = ./game;
+              fileset = fs.unions [
+                ./game/src/lib.rs
+                ./game/Cargo.lock
+                ./game/Cargo.toml
+                ./game/pyproject.toml
+              ];
+            };
+          nativeBuildInputs = [ python_version ];
+          # doCheck = true;
+          # buildInputs = [];
+        };
+
+        crate_artifacts = craneLib.buildDepsOnly (
+          crate_cfg
+          // {
+            pname = "${project_name}-artifacts";
+            version = project_version;
+          }
+        );
+
+        # Build the library, then re-use the target dir to generate the wheel file with maturin
+        crate_wheel =
+          (craneLib.buildPackage (
+            crate_cfg
+            // {
+              pname = project_name;
+              version = project_version;
+              cargoArtifacts = crate_artifacts;
+            }
+          )).overrideAttrs
+            (old: {
+              nativeBuildInputs = old.nativeBuildInputs ++ [ pkgs.maturin ];
+              buildPhase = old.buildPhase + ''
+                maturin build --offline --target-dir ./target
+              '';
+              installPhase = old.installPhase + ''
+                cp target/wheels/${project_name}-${project_version}-${wheel_tail}.whl $out/
+              '';
+            });
+      in
+      rec {
+        packages = {
+          default = crate_wheel; # The wheel itself
+
+          # A python version with the library installed
+          pythonpkg = python_version.withPackages (ps: [
+            (lib.python_package ps)
+          ]);
+        };
+        devShells.default = craneLib.devShell {
+          packages = [
+            (pkgs.python3.withPackages (ppkgs: [
+              ppkgs.torch
+              (lib.python_package ppkgs)
+            ]))
           ];
         };
-      });
-    };
+        lib = {
+          # To use in other builds with the "withPackages" call
+          python_package =
+            ps:
+            ps.buildPythonPackage rec {
+              pname = project_name;
+              format = "wheel";
+              version = project_version;
+              src = "${crate_wheel}/${project_name}-${project_version}-${wheel_tail}.whl";
+              doCheck = false;
+              pythonImportsCheck = [ project_name ];
+            };
+        };
+      }
+    );
 }