nixos-combined-flake/modules/home-manager/games/doom/eternity.nix

{
  pkgs,
  config,
  lib,
  ...
}: let
  cfg = config.games.eternity;
in
  with lib; {
    options = {
      games.eternity.enable = mkEnableOption "eternity-engine";
    };
    config = mkIf cfg.enable {
      home.packages = with pkgs; [
        eternity
      ];
    };
  }