Having downloaded and installed the first of these (Secret of..), the program will not run. A window pops up, stating that "the code execution cannot proceed as X3DAudio1-6.dll was not found". Re-installing as advised, twice, did not help. Is this a missing .dll from the download, or is it part of Windows 10 OS which I use?

What OS are you using? Inform us more on what you have so we don't have to ask so many questions, ok? :-)

Anyway, two things you could do:

1. Download and reinstall directx9c

or

2. Re-register X3DAudio1_6.dll from an elevated command prompt (Windows XP, Vista, 7, 8, and 10):

Click the Start button.
Type "command" in the search box... DO NOT hit ENTER yet!
While holding CTRL-Shift on your keyboard, hit ENTER.
You will be prompted with a permission dialog box.
Click Yes.
Type the following command: regsvr32 /u X3DAudio1_6.dll.
Hit ENTER. This will UN-REGISTER your file.
Type the following command: regsvr32 /i X3DAudio1_6.dll.
Hit ENTER. This will RE-REGISTER your file.
Close the command prompt window.
Re-start the program associated with X3DAudio1_6.dll error.

If that doesn't work you might have a corrupted files/OS... if others have the same there might be a problem with the game.

I don't have any Monkey Island games but judging by the error I highly advise you download and install DirectX End-User Runtimes (June 2010)

Download and install this - https://www.microsoft.com/en-us/download/details.aspx?id=8109

edit:fsck, ninja'd 2x :D

Hi All,

I just bought the Monkey Island games... great offer, could not resist etc.

Anyway I am using Win10 and I had this same issue complaining about X3DAudio1-6.dll :-(

Downloading the 2010 DX Runtimes, as advised here, was the answer:

1. Download the file from MS (from the link given in earlier posts.
2. Extract to a suitable folder - I had to create of outside of the installer for this.
3. In the extracted file, run the setup.

After this, Monkey Island 1 (SE) worked for me - hurrah!

Try this for the first two games (worth it):

http://gratissaugen.de/ultimatetalkies/

For Curse just use ScummVM.

Escape I believe is compatible with another port called Dreamm (not sure is available for Windows though, but maybe is compatible with ScummVM now? Check it out).

Way better than playing the vanilla releases from GOG.