Anno 1404 originally allowed players to freely modify the game without restriction. The developers released a editing tool to assist players in modding. Modding game variables, names, and algorithms was also possible through manual editing of .XML, .TXT, and other files.
However, version 1.1 of Anno 1404 made it so any modding whatsoever would disable the ability to get achievements, medals, and accolades. This greatly diminished the modding community.
Modding after Patch 1.1
For a long time players thought it was impossible to get around the disabling of achievements when modding was being used. However, there is a way to mod the game and have the game not realize it's been modded. This is because the developers didn't include any proper checksums or other encryption techniques, fortunately.
Modding is done by adding modified files to or deleting current files from .rda files, specifically the addon\patch0.rda for Venice and maindata\patch2.rda for Anno 1404. These two patch files are used because the game gives them precedence over all other .rda files.
So to mod Venice:
- Locate the "root game install folder\addon\patch0.rda" file. If you don't have this file, it's because you aren't running Venice version 2.1.
- Create a backup of the patch0.rda, by copying and pasting it somewhere.
- Download RDAExplorer and unpack it anywhere.
- Run it.
- Go to File->Open and browse to your install\addon directory and pick to open the patch0.rda.
- Make sure you DO NOT EVER pick the File->Open (Read only) option! Doing so will break achievements and medals!
- Now extract whatever files you want to edit. You'll have to figure out what you want to mod and which files must be edited. Not all files are in the patch0.rda. Refer to the External tools page.
- Make whatever edits to the .txt or .xml or .dds files or whatever. Now put the changed files in a separate folder with the appropriate directory structure. For instance, if you edited the quests.xml file, make sure it's in "yourmod\addondata\config\quests\".
- Make sure you have patch0.rda open in RDAExplorer.
- Go to Tools->Add folder as root … then search for the folder you did your edit work in. Select it and hit OK. This will automatically replace or add files to the .rda, even though no confirmation is provided.
- You can continue doing the Tools->Add folder as root… option if you have other folders to add.
- Once that’s done, just go to File->Save. Use whatever default compression settings it has selected, and hit OK. Changing the compression settings can cause the game to not work.
- Now you’re done. If you did things correctly, the game won’t realize you’ve modded it and you’ll have whichever mods you picked.
- Run the game and make sure there's no message in the very bottom-right of the main menu saying "Game modification detected..."