Major config overhaul: use custom modules, setup for multi-host config, and less boilerplate

modules/system/gaming/default.nix

@@ -0,0 +1,20 @@
+{ lib, config, pkgs, ... }:
+
+let
+  cfg = config.systemSettings.gaming;
+in {
+
+  options = {
+    systemSettings.gaming = {
+      enable = lib.mkEnableOption "Enable Steam and games";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [ "steam" "steam-unwrapped" ];
+    hardware.opengl.driSupport32Bit = true;
+    programs.steam.enable = true;
+    environment.systemPackages = with pkgs; [ pkgs.steam gamemode prismlauncher ];
+    programs.gamemode.enable = true;
+  };
+}