nixos/modules/common/gaming/steam.nix

{ config, pkgs, lib, ... }:
{
  options = {
    steam = {
      enable = lib.mkEnableOption {
        description = "Enable Steam";
        default = false;
      };
    };
  };
  config = lib.mkIf (config.gui.enable && config.steam.enable) {
    programs.steam = {
      enable = true;
      remotePlay.openFirewall = true;
      dedicatedServer.openFirewall = true;
    };
  };
}