Steam – When do Steam Workshop mods download/sync

I'm sure they're vulnerable in some way, as hardly any software is free of potential exploits, however, I havn't heard of any active exploits in Gamebryo games. As far as i know, mods have no way of interacting with anything outside of the game. Some tools, such as SKSE and ScriptDragon, make it possible for them to access configuration files in their directories, but that shouldn't be a big concern. Also, remember that the CK is not the only way to make .ESP files. Many programs have been vulnerable to maliciously-modified files. I would say the risk is fairly low, but it is not non-existent.

If you deeply care about security, I would advise against immediately downloading new mods, and letting the other people test them first. The added benefit of that approach is that mature mods are less likely to break your save or have dirty edits and such.

To answer the new question, mods can modify quite a bit, including most visuals and many game mechanics. There are some things that mods cannot do, such as add skill trees (Though they may emulate them in a way). I failed to locate any details on exactly what files the Steam Workshop will accept (A detail one would image should be on their wiki), but at the very least they will be .esp files and .bsa archives, textures, models, sounds, Papyrus scripts and text files.

First things first before I get to the advice: Nexus Mod Manager is beta software. If you're experiencing problems with it, consider reporting the problem so that the coders and other users on the official beta feedback forum can read about it and any bugs can be fixed. If there are installation problems, they'll want to know about it and it's more likely to be fixed there than by asking here.

In the meantime, it might help to know that a mod manager is optional—you can install mods without ever touching Nexus Mod Manager. Since it's beta-quality software and you've probably just run into a bug, I'd advise learning how to cut out the middleware and install mods manually. Most mods are simple and it's just a matter of putting the right files in the right place.

Here's the simplified overview of how to install a mod manually:

1. Download the mod you want to install and unpack it to a temporary folder. You'll want to use 7zip for this, because it can handle the popular archiving formats that Skyrim modders pack their mods with. If you have the option of multiple file formats, pick "7zip", the one that end with .7z. Failing that, get the .zip file.

2. Look inside the freshly unzipped mod folder. Look for the readme file. This will tell you what you need to do to install the mod correctly.

   Sometimes the mod author will tell you to "put the files in your data folder" and you'll swear at them for not explaining what that is. They mean \Steam\SteamApps\common\skyrim\Data. If they tell you to put files in "your Data folder", they mean there.

   If they're not clear about what files to put there, you have to look a bit closer at the mod. If you have a folder named like the mod, don't put that folder in your Data folder—you want to put the contents in your Data folder. Same thing if your unpacked mod has a Data folder—you don't want to put that in your Data folder (which would end up with a Data/Data/[mod files] layout that doesn't work), you want to put what's inside it in your Data folder. You want to be looking for folders like textures and meshes, and files that end in .esp or .esm to dump into your Data folder.

   (If you're on Windows XP, you may want to disable UAC to simplify this process, since the game folder is in a UAC-protected area.)

3. Start Skyrim's launcher. If your mod had any .esp or .esm files (these are "plugin" files), you need to tell Skyrim to load these up when it starts. If there weren't any (for example, most texture mods that don't add new items won't have a plugin file), then Skyrim will find the mod files all by itself and you're done.

   So if there are plugin files, the launcher will let you activate them if you click on "Data Files". There will be a list of things, including Skyrim.esm, with checkboxes beside them. Make sure your new mod's plugin files have checkmarks, hit OK to close that window, and then click "Play" to enjoy. Once you've told Skyrim about a plugin file, it remembers, so you only have to do this once for a new mod, assuming it has plugin files.

If you want to read that all again using different words (which sometimes helps immensely in figuring this stuff out), there's a short article on the Nexus Wiki: How to install Skyrim mods. Manual installation is covered in item (8).

Finally, the Nexus forums and official Bethsoft Skyrim forums are very helpful when you run into trouble.