On
Windows

The button above. The file is ODG-Ops.zip, about 56 MB. It is the only file you need.

In Chrome or Edge, click the arrow next to the download and pick Show in folder. In Firefox it is Open Containing Folder. You want the file sitting in Explorer, not open in a window.

Right-click ODG-Ops.zip, pick Extract All, then Extract. Unzip and extract mean the same thing. Desktop or Downloads is fine. Do not put it in the game folder.

Extracting makes a new folder next to the zip. Go into it and run ODG Ops. That one file does everything else for you: the loader, the mods, the maps. You do not unzip anything else, ever.

The first run downloads about 4.5 GB. Leave it alone until the line at the top reads UP TO DATE. Then press LAUNCH. The missions are on the Cerberus laptop under DUKE'S OPS.

You both need the same pack version. The launcher shows it at the top. Let it finish updating before you host.

Double-clicking a zip opens it like a folder, and ODG Ops is sitting right there looking ready. Run it from in there and it cannot write anything, so nothing installs. Extract first, then run it from the folder that appears.

Desktop, downloads, a folder of its own, anywhere but there. The launcher writes into the game folder as part of its job, and keeping its own files in the same place tangles the two together.

Do not unzip melonloader.zip. It is on the release page because ODG Ops downloads it for you. Unzip ODG-Ops.zip and nothing else. Two copies of the loader in the game folder and it stops starting at all.

ODG-Ops.zip is the whole thing. Everything else on the release page is there because ODG Ops goes and gets it. Grab a file on its own and you get that file and nothing around it.

Windows still needs one, whatever your RAM says. With it off the game runs out of memory while it loads the menu and dies on startup perhaps half the time, which reads like a broken mod and is not one. Leave it on system-managed.

The launcher asks for your OPERATOR folder once and keeps it. Move the game or rename that folder later and it is pointing somewhere that no longer exists.