full rewrite, first commit

modules/nixos/apps/steam/default.nix

@@ -0,0 +1,27 @@
+{
+  options,
+  config,
+  lib,
+  pkgs,
+  namespace,
+  ...
+}:
+with lib;
+with lib.${namespace};
+let
+  cfg = config.${namespace}.apps.steam;
+in
+{
+  options.${namespace}.apps.steam = with types; {
+    enable = mkBoolOpt false "Whether or not to enable support for Steam.";
+  };
+
+  config = mkIf cfg.enable {
+    programs.steam.enable = true;
+    programs.steam.remotePlay.openFirewall = true;
+
+    hardware.steam-hardware.enable = true;
+
+    environment.systemPackages = with pkgs; [ steam ];
+  };
+}