Finally switch to flakes.

nixos/desktop/gaming.nix

@@ -0,0 +1,23 @@
+{pkgs, ...}: {
+  # Enable Gamemode to boost games
+  programs.gamemode = {
+    enable = true;
+    settings.general.renice = 10;
+  };
+
+  # Enable hardware like the Steam Controller
+  hardware.steam-hardware.enable = true;
+
+  # Enable the Steam client
+  programs.steam = {
+    enable = true;
+    remotePlay.openFirewall = true;
+    dedicatedServer.openFirewall = true;
+    extraPackages = with pkgs; [
+      steam-run heroic prismlauncher
+    ];
+    extraCompatPackages = with pkgs; [
+      proton-ge-bin
+    ];
+  };
+}