Everything you need to get in. One unzip, one click.
Portable packs · no installers · bring your own commercial data where the law says so

The portable pack: Zandronum 3.2.1 + the Brutal Doom Community Expansion + a smart launcher. Unzip anywhere, double-click PLAY HELLHOUSE.bat — it finds your own Doom II, grabs the live season, and drops you in.
You supply your own doom2.wad (Steam / GOG) — the one file we can't host. Everything else auto-downloads.

The portable pack: the FTEQW engine + the free shareware Episode 1 + a one-click launcher that auto-connects to the server. Nothing to install, nothing to buy — anyone plays Episode 1 instantly.
Episode 1 is on us. All four episodes need registered Quake — own it on Steam / GOG and drop your pak1.pak in.

No pack to grab — DayZ handles it. Join through the DZSA Launcher (DayZ Standalone Launcher) and it auto-installs the whole modlist and drops you on the island. Or add the server in the in-game browser.
You supply DayZ itself (Steam). The 29-mod loadout installs itself the first time you connect.