Mods from our catalog and most other sites come as an archive — .zip, .rar or .7z. The built-in Windows Explorer only opens .zip; .rar and .7z require a third-party tool. That's why almost everyone who installs mods manually — for HOI4, RimWorld, Oxygen Not Included or People Playground — eventually asks: which program to use and how to extract the archive correctly so the mod actually works. Here is how to do it with the free 7-Zip archiver.
What is 7-Zip and where to get it
7-Zip is a free, open-source archiver. It weighs about 2 MB and supports every format you'll meet among mods: .zip, .rar, .7z, .tar.gz and dozens more. Download it only from the official 7-zip.org site — copies on random sites often bundle adware.
- Download the installer from the official site: for 64-bit Windows pick the file like «7z2501-x64.exe» (the version number may differ).
- Run it and press «Install» — installation takes a few seconds.
- Right-click any archive: a «7-Zip» entry should now appear in the context menu.
On macOS use Keka or The Unarchiver; Linux usually ships with an archive manager (p7zip). Everything else works the same on any system.
How to extract a mod archive
- 1Download the mod archive — for example from our HOI4 catalog or RimWorld catalog.
- 2Right-click the archive → «7-Zip» → «Extract Here». The files appear next to the archive.
- 3Even better, use «Extract to <archive name>\»: the content lands in its own folder and won't mix with other files.
- 4Check what's inside: an HOI4 mod has a .mod file plus common, history and gfx folders; a RimWorld mod has an About folder with Common and Assemblies subfolders.
- 5If there's another archive inside (.zip inside .7z, etc.) — extract that one too: modpacks are often packed this way.
- 6Copy the extracted files into the game's mods folder. For HOI4 it's
Documents\Paradox Interactive\Hearts of Iron IV\mod(see the full HOI4 mod installation guide); for RimWorld it's theModsfolder (see how to install RimWorld mods).
Don't extract by double-clicking and dragging files out of the archiver window — it's easy to miss some of them. Right-click → «Extract» is more reliable.
If the archive won't open
- «Cannot open file as archive» — the download didn't finish or the file got corrupted. Delete it and download again, preferably with another browser.
- A password is requested — files on prime-mods.ru are never password-protected. If the source site protects its archive, the password is usually in the description.
- The archive extracted, but there's no mod inside — check nested folders: the mod is often two levels deeper than it looks.
Common mistake: one folder too many
The HOI4 launcher and RimWorld both expect an exact folder structure: for HOI4 the .mod file must sit in the mod folder next to the mod's folder; for RimWorld the mod folder with About must be right inside Mods. If extraction produced a folder inside a folder with the same name, just move the contents one level up. This is the most common reason a mod «was downloaded but never appeared in the launcher».
All files on prime-mods.ru are .zip — Windows can extract them even without 7-Zip. But 7-Zip is faster and consistent, and it is a must for mods from other sites, where .rar and .7z are common.
Done — the archive is extracted and the mod is in place. Continue per game: installing HOI4 mods without Steam, HOI4 mod load order, installing RimWorld mods. If the mod doesn't work, start with HOI4 mod errors and conflicts.