Welcome to the guide.

Open Transport Tycoon Deluxe comes with a series of freeware graphics, sounds and music which are pretty good!

However, some of us remember playing the original Transport Tycoon Deluxe on DOS or Windows and would like to play OTTD using the pixel graphics and midi sounds we remember.
This guide will tell you how to do it.

The first step is to obtain the original game files.

They are not distributed with OTTD by default due to copyright issues. Basically, you should own the original game and copy the files from the original installation. There were two versions of the game, the DOS version and the Windows version. If possible, use the Windows version.

In reality though, Transport Tycoon Deluxe is abandonware and there are many sites providing free download of the game, for example Abandonia. Abandonware is usually considered a "gray area", which is why you have to obtain the original files yourself if you choose this option.

Either way, the original game size should be very small, full game in a zip file usually has less than 10 MB.

Once you have downloaded or installed the original game anywhere, open Steam, right click Open TTD -> Properties, switch to Local Files tab and click the Browse button.

In the folder that just opened, create two new empty folders named:
data
gm

Now, navigate to the original game's folder and copy these 6 files into the data folder you just created:
sample.cat
trg1r.grf
trgcr.grf
trghr.grf
trgir.grf
trgtr.grf

If you used the DOS version of the original game, your graphics files may be named like this:
TRG1.GRF
TRGC.GRF
TRGH.GRF
TRGI.GRF
TRGT.GRF

Next, navigate to the original game's folder, go to gm folder and copy all files into the gm folder you created. There should be 22 files named from
gm_tt00.gm
to
gm_tt21.gm

Now we have the files, start the game from Steam.

In the game's main menu, select Game Options. At the bottom of the new window, you should see three options named Base graphics set, Base sounds set and Base music set. Click on each of them and you should see a new original_windows option. Select it, then click the X in the upper right corner to save the settings. You should see and hear the difference in the background instantly.

You can now enjoy the original Transport Tycoon Deluxe with all the modern improvements of OTTD.

That's it!

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