When I launch the Two Worlds application after a successful install the following error message appears:
"This application has failed to start because X3DAudio1_1.dll was not found. Re-installing the application may fix this problem"
This error occurs every time, and I have re-installed the game with no success.
I've submitted a support ticket on the issue, with a DxDiag file included, just thought I'd post on the forums, see if anyone else has found this?

Thanks a lot Grombart, installed Direct X 9 and it launches fine now :) I thought I already had it on this system but I reinstalled and it worked, so presumably not!

Glad i could help. :)
Hope you enjoy the game!

Full DX9c file here :
http://www.softwarepatch.com/windows/directx.html
or customizable download from Microsoft :
http://www.microsoft.com/downloads/details.aspx?FamilyID=2da43d38-db71-4c1b-bc6a-9b6652cd92a3&displaylang=en

Thank you so much.

No problem - enjoy the game :)

I sure wouild be nice if they updated the game to work with DX11. I'm going to have to go back and forth to play star craft. Not worth it. THIS IS DEFINITELY NOT SOLVED. More like Half ASSED

No company is going to upgrade an older game to be DX11 compatible. And there's no 'going back and forth'. Just install DX9 and you're good to go. A game will use DX9 resources if it needs it and it will use DX11 if it needs that. There's no going back and forth involved. You can have both DX9 and DX11 installed on the same machine with no issues.

I just want to add some info on this problem. I originally downloaded and reinstalled this game about 3 different times and I was still receiving the "d3d dll" error. First I installed the updated version of Nvidia's physX (IIRC) and it still was giving an error code on boot. So, I tried what was suggested in this thread to install the latest version of 9.0c from the 2nd link provided for the genuine microsoft download, and voila! It worked beautifully, just reset my graphics to 1920 x 1080 with 4x AA and it looks gorgeous!. I suggest to anyone who is having problems to do a clean install and follow what it suggests in this thread, it works :)

Looks like Coelocanth beat me to it, but just to reiterate: No "back and forth" required. You can have DX9 and DX11 installed at the same time. In fact, I do, right now. The new games and older games work great without any problems.

I had this problem, thank you for the solution (+1 for you!)