DLC mod FAQ for Mass Effect 3
To help the staff, users, and modders of Nexus, a few of us senior mod authors in the Mass Effect modding community have written up this FAQ about DLC mods. Short of textures and coalesced modding, DLC mods are the most common type of mod for ME3 and they are becoming more common for ME1 and ME2. It's important everyone understands the basics.
This FAQ is not meant to be a complete reference. For an introduction to the various mod formats available for ME3 read this. To find out if a mod should be released as DLC in the first place read this.
We may build onto this FAQ or create new ones as the need arises.
Q: What is a DLC mod?
A: A mod which functions similarly to official DLCs from Bioware. The mod is in its own folder, inside the DLC folder of Mass Effect.
Q: How are DLC mods structured?
A: The structure of every DLC mod follows official BioWare DLC (that's been extracted). There are a few folders involved, and inside those folders are files, most of which are "PCCs". PCCs are compressed archives similar to a ZIP file, and are the game's main way to store its content. Each PCC stores a complete game "level", such as Normandy's cargo bay. This means a single PCC contains level objects, NPCs, dialogues, cutscene data, meshes, materials, powers, texture mipmaps (and sometimes full textures), and much more. The base game alone contains almost 2500 PCCs and all the DLC add even more. DLC mods contain copies of these same PCCs, with a blend of edited and vanilla content.
Q: How do I install a DLC mod and does it require a separate program?
A: Every mod is different. Most mod authors provide instructions, so it's important to read them thoroughly. Ultimately, any DLC mod installation involves adding the DLC mod folder to the Mass Effect DLC directory. Whether this is done via an automated installer, a separate tool, or manually (via copy/paste), that will change for each mod.
Q: What is mount value?
A: Mount value, also called "mount priority", is how the game prioritizes content. Think of it as a built-in load order. In the case of duplicate files (in the base game, official DLC, or DLC mods) the file with a higher mount value/priority is loaded by the game. The lower file is ignored. For example, the official Leviathan DLC overrides the Normandy CIC file from the main game. Likewise, the Citadel DLC does the same above Leviathan. And EGM (Expanded Galaxy Mod) overrides a variety of official files, preserving some functionality of the main game files while adding what is necessary for EGM to work.
Q: In general, how can I tell if DLC mods will work together?
A: Look at the contents of the DLC mod and for any files with the same name. If you don't see any files of the same name, everything is likely to work. If you do see files of the same name, whichever mod has the higher mount value will be the only file to load in the game.
In addition, if you see two mods editing the exact same file and there is no patch available from either mod author, then the mods are not fully compatible. There is a "conflict", and one of the mods will override the changes of the other mod. The game may not break if you use both, but know that whichever mod is mounted higher is going to control the changes you see in the game. This may affect your playthrough in unpredictable and unintended ways.
Q: What is a "compatibility patch"?
A: Due to the file structure of the ME trilogy, conflicts and compatibility is a larger problem than with most games. DLC mods come with edited game files, not a newly-named ESP of changes like Skyrim.
Modders can choose to resolve file incompatibilities with a "patch". The fine technical details of patches can differ, but most of the time it amounts to combining the edits found in both mods, allowing the player to experience both. If there is a thematic conflict -- one mod edits an NPC in one way, and the other mod edits the same NPC in a different way -- then it's up to the two authors to decide how they want to build the patch.
Patches, by nature, always contain the creative content found in two mods and can only be released with the permission of both authors. Compatibility patches for every conflict are likely to not be available, especially as modding for the ME trilogy continues to grow.
Q: I've modded Skyrim and Oblivion before. Looks like I can just reorder the priority for mods using ME3 Mod Manager.
A: Avoid this. Remember, unlike Skyrim, DAO, and a variety of other games, DLC for the Mass Effect trilogy contain a built-in load order. When an author creates their mod they look at the mount values used by official DLC and other mods, and set theirs accordingly. They also design patch content assuming those values are in place. If they change, mod functionality can be affected.
If you choose to change mount values anyway, you're taking a risk and your results will vary. Some mods are fine with this type of rearranging, but more complex mods (like ones that alter story) will have problems. Mod authors may not help troubleshoot technical problems that result from a user tampering with mount priority, and any help they provide will only be of use if you disclose that you've changed the mount.
Q: When is a mod "deprecated"?
A: Deprecation is a term frequently used in coding and software. Generally, it indicates a feature or version that shouldn't be used as it's been superseded by something newer or more complete. Often deprecated software is removed or becomes unsupported by the creator.
When it comes to mods, deprecation commonly occurs if the game itself is updated and the mod no longer works. Deprecation can also occur when a mod author releases a new version of their mod, resulting in them no longer supporting (and potentially removing) the old version. An author combining several smaller mods into one larger mod is also another cause of deprecation.
Mods, generally, do not deprecate each other. In short, feature redundancy/similarity should not be confused with deprecation. For example, ME2Recalibrated contains edits similar to the Illium Movie Mod and Arrival Triggering Mod. However, ME2Recalibrated doesn't "deprecate" these other mods. They remain valid choices for any user, as ME2Recalibrated contains a significant amount of other content that the player may not wish to use.
We hope this helps everyone.
-Deager, author of CEM
-AVPen, author of Tali Romance Mod
-Kinkojiro, author of EGM
-JohnP, author of JAM