Music replacement project

The OpenTTD Music Replacement Project is an on-going project dedicated to creating new Base Music packs for distribution with OpenTTD.

Music Replacement Project logo in OpenGFX style, created by jvlomax



As OpenTTD is a clone of Transport Tycoon Deluxe, a lot of effort was put into replacing the original TTD graphics and sounds with new, open-source and freely-distributable graphics and sounds. As the project neared the 1.0.0 milestone at the end of 2009, however, there had not been a lot of discussion about replacing the TTD music in the same manner. The OpenTTD Music Replacement Project was started by Kevin Fields (kamnet) on the message boards on December 26, 2009.

The OpenTTD Music Replacement Project is a community-based effort to provide new base music files which can be distributed with the game and completely free OpenTTD from any dependencies on having the TTD files in order to enjoy a full, robust game.



Any member of the OpenTTD community can contribute to the project. The projects are organized on the official OpenTTD forums at, but collaboration and contributions can come from any player and any website or community.

Music Style

There are no restrictions on the musical styles which may be included.


The preferred license for releases is GNU Public License v2. This is the same license that is distributed with OpenTTD, and allows for files to potentially be distributed with the game without any conflicts. However, as each project is independently organized, and not all sources may be freely distributable, any license may be used so long as it is clearly stated and documented.


For music to be included and distributed, the author(s) must be the legal owners of the copyright for the files, or they must obtain permission from the copyright holders.

Music itself has two different sets of copyright holders: the owner of the song (for example, the songwriter, or the music label) and the performer (the artist or composer of the music work). While many free MIDI music sites have music composed by individuals who distribute it freely, many of the songs are commercial works whose copyrights are retained by others, and have not given permission to the composer who posted it online. Even with original works posted online, you still must also have the permission of the composer to distribute them.

When submitting music for inclusion in an OpenTTD Music Replacement Project set, please also include information about the copyright holder(s) of the music.

Frequently Asked Questions

What music formats are used?

At this time, only MIDI music files (.mid or .gm) are acceptable for inclusion. This is due to the fact that the original TTD game used MIDI files, and OpenTTD is a faithful open source clone aimed at being backwards-compatible with TTD. In addition, the files must conform to the General MIDI standard and must not contain any sound fonts or features which require additional software or hardware dependencies.

Why can I not use MP3 or OGG files?

At this time there is no support in the game for playback of MP3 or OGG files. There have been discussions about creating a new in-game music player, but those efforts have not yet materialized. The development of such a music player inside the game is beyond the scope of this project.

What is a base music pack?

A base music pack is composed of a meta data file (with a file extension of .obm), along with a collection of MIDI files (with a file extension of either .mid or .gm).

The meta data file will contain five sections:

Metadata - the name, version number and description of the music pack

Files - the file names of each MIDI file included, each with its category as described below

MD5 - the MD5 checksum of each file, to ensure that they are the original and correct file

Names - linking of each file name to a human-readable title that displays in the in-game player

Origin - a place from which a copy of the music pack can be obtained, displayed if the files get corrupted. Even though some music sets use this field for other purposes, such use may not be useful.

The music pack can support a total of 31 MIDI files. The songs are organized into four categories: Theme (the theme song for the music pack), Old Style (old_0 to old_9), New Style (new_0 to new_9) and Ezy Street (ezy_0 to ezy_9). These are the categories as named by the original TTD game and the music in each category matched that theme. (New music packs do not have to adhere to this style, or any style at all, but still have to define their files in these styles.) The Theme category can only list one song, while the other categories can have up to ten songs each. Each category does not have to be filled with ten songs, but if there are not ten songs in each category there must still be a place listing in the meta data file, which can be left blank.

An example of an .obm meta file can be found in OpenMSX.