Migrated from import based to config based

modules/system/applications/steam.nix

@@ -0,0 +1,31 @@
+{ config, lib, ... }:
+
+with lib;
+
+let
+  cfg = config.settings.applications.steam;
+in {
+  options = {
+    settings.applications.steam.enable = lib.mkOption {
+      type = with lib.types; bool;
+      description = ''
+        Enable steam
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    nixpkgs.config.allowUnfree = true;
+    nixpkgs.config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
+      "steam"
+      "steam-original"
+      "steam-run"
+    ];
+
+    programs.steam = {
+      enable = true;
+      remotePlay.openFirewall = true;
+      dedicatedServer.openFirewall = true;
+    };
+  };
+}