OpenTTD uses its own directory to store its required 3rd party base set files (see section 4.1 ‘Required 3rd party files’) and non-compulsory extension and configuration files.
See below for their proper place within this OpenTTD main data directory.
The main OpenTTD directories can be found in various locations, depending on your operating system:
The current working directory (from where you started OpenTTD)
For non-Windows operating systems OpenTTD will not scan for files in this directory if it is your personal directory, i.e. ‘~/’, or when it is the root directory, i.e. ‘/’.
C:\My Documents\OpenTTD (95, 98, ME)C:\Documents and Settings\<username>\My Documents\OpenTTD (2000, XP)C:\Users\<username>\Documents\OpenTTD (7, 8.1, 10, 11)~/Documents/OpenTTD$XDG_DATA_HOME/openttd which is usually ~/.local/share/openttd
when built with XDG base directory support, otherwise ~/.openttdC:\Documents and Settings\All Users\Shared Documents\OpenTTD (2000, XP)C:\Users\Public\Documents\OpenTTD (7, 8.1, 10, 11)/Library/Application Support/OpenTTDC:\Program Files\OpenTTD/usr/games/usr/share/games/openttdThe application bundle (macOS only)
It includes the OpenTTD files (grf+lng) and it will work as long as they are not touched
Different types of data or extensions go into different subdirectories of the chosen main OpenTTD directory:
| data type | directory | additional info |
|---|---|---|
| Config File | (no subdirectory) | |
| Screenshots | screenshot | |
| Base Graphics | baseset | (or a subdirectory thereof) |
| Sound Sets | baseset | (or a subdirectory thereof) |
| NewGRFs | newgrf | (or a subdirectory thereof) |
| 32bpp Sets | newgrf | (or a subdirectory thereof) |
| Music Sets | baseset | (or a subdirectory thereof) |
| AIs | ai | (or a subdirectory thereof) |
| AI Libraries | ai/library | (or a subdirectory thereof) |
| Game Scripts (GS) | game | (or a subdirectory thereof) |
| GS Libraries | game/library | (or a subdirectory thereof) |
| Savegames | save | |
| Automatic Savegames | save/autosave | |
| Scenarios | scenario |
The (automatically created) directory content_download is for OpenTTD’s internal use and no files should be added to it or its subdirectories manually.
Place 3rd party files in shared directory (or in personal directory if you do not have write access on shared directory) and have your openttd.cfg config file in personal directory (where the game will then also place savegames and screenshots).
You can install OpenTTD on external media so you can take it with you, i.e. using a USB key, or a USB HDD, etc. Create a directory where you shall store the game in (i.e. OpenTTD/). Copy the binary (OpenTTD.exe, OpenTTD.app, openttd, etc), baseset/ and your openttd.cfg to this directory. You can copy binaries for any operating system into this directory, which will allow you to play the game on nearly any computer you can attach the external media to. As always - additional grf files are stored in the newgrf/ dir (for details, again, see section 4.1).
OpenTTD can read files that are in an uncompressed tar (archive), which makes it easy to bundle files belonging to the same script, NewGRF or base set. Music sets are the only exception as they cannot be stored in a tar file due to being played by external applications.
OpenTTD sees each tar archive as the ‘root’ of its search path. This means that having a file with the same path in two different tar files means that one cannot be opened, after all only one file will be found first. As such it is advisable to put an uniquely named folder in the root of the tar and put all the content in that folder. For example, all downloaded content has a path that concatenates the name of the content and the version, which makes the path unique. For custom tar files it is advised to do this as well.
The normal files are also referred to by their relative path from the search directory, this means that also normal files could hide files in a tar as long as the relative path from the search path of the normal file is the same as the path in the tar file. Again it is advised to have an unique path to the normal file so they do not collide with the files from other tar files.
The configuration file for OpenTTD (openttd.cfg) is in a simple Windows-like .INI format. It is mostly undocumented. Almost all settings can be changed ingame by using the ‘Advanced Settings’ window.
When you cannot find openttd.cfg you should look in the directories as described in this document. If you do not have an openttd.cfg OpenTTD will create one after closing.