I installed Two Worlds on 2 PCs both having nVidia gForce cards and Windows 7 x64. I have declined the installation of Ageia PhysX by the game installer and Two Worlds runs fine on both machines using the PhysX software bundled with the nVidia drivers.

This doesn't seem to be the case for everyone... also if someone is using an AMD graphics card, the legacy PhysX drivers help. Good to know that it does sometimes work "out of the box" though.

Indeed, I wanted to clarify this for people using nVidia video cards.

Ah. That makes sense. I guess Nvidia users can try running without the legacy drivers.

For me it worked from the beginning and continued to work flawlessly after several driver/PhysX updates.

I use the 9.12.0613 Physx drivers.

http://www.nvidia.com/object/physx-9.12.0613-driver.html

Works with Windows 8, and Windows 7. As well as all my games that require physx. So me personally, I install those drivers, and leave them be. That's all I ever needed for Windows 7 and Windows 8.

I have an ATI video card, just to let you know.

I have a system-wide installation of PhysX running (so that each game doesn't have to separately install it) and have disabled the physX version that ships with the Gog version, and using the RADEON executable, the game is much, much better looking...! I was surprised, actually, by the difference because I didn't expect any. The 9.12.0613 Physx drivers seem to support all of my PhysX games. The older PhysX driver included with the game seemed to actually degrade the IQ somehow. Strange.

Just got a new Windows 8.1 with Nvidia Geforce... Thought my Two Worlds copy would finally run properly..
But Now it won't start.
I read this thread but was no help... I tried to get some drivers installed but they are said to be older and ignored...
Argh...

"The program can't start because XINPUT1_3.dll is missing from your computer. Try reinstalling the program to fix this problem."

Xinput1_3.dll is part of DirectX. Go to the Microsoft web site and download the DirectX installer.

oh dammit what a mistake :) I was sure I had checked this had DirectX installed... Too excited probably.. sorry

Thank you! The game, when installing said my Phsyx drivers were newer and so wouldn't install the older drivers and so the game would not start. Downloaded the linked driver and now all works perfectly.

Just in case this info is useful to people in the future, I have a Nvidia card running the latest version of drivers (337.88) which needed the legacy driver update. +1 to OP for info :)

YES!!!!
This fixed everything for me!
Now I can play Two Worlds again!
Thanks OP

I have the Intel hd 3000 integrated graphics in my laptop. I installed Two Worlds, and it worked great. A couple years later, I reformatted my laptop. Now trees, boulders, fences, buildings, etc. are only visible when I'm looking at them sideways. If I'm facing right at them they're invisible. All NPCs and enemies show up normally. This puts me at a disadvantage in fights, and also ruins my sense of being part of the game.

Does anyone have any ideas of what might have happened? I've updated all my drivers, so I don't think that's it. I also downloaded the Two Worlds control panel, but it didn't help with my problem. I'm at a loss to what to try next. I'd had the urge to run through the game again, but don't want to do it with invisible boulders

Fixed the problem for me also (following an Nvidia Forceware update) - thumbs up for OP, thumbs down for Nvidia and please GOG, make this thread a sticky!