I dont know CodeWeavers and I know to less about Macs, but some general hints, because the chances are little that you will find someone that knows the solution:

1. Check your video graphics settings. Especially stuff like Anti Aliasing or VSync can cause such problems.
2. Check the rights the game runs with, can it access all the necessary files and so? Try to run it as administrator (dont ask me how this works with CodeWeavers on Mac).
3. Check the configuration of the game itself (dont ask me where you can find it, I had it also to look up), especially fullscreen / windowed mode, resolution, enabled VSync, AA, maybe shader or DX version if possible to choose.
4. I had similar problems on a windows machine with missing or broken video codecs. As far as I know the game needs a special version of the codec itself. Not sure if the game wont run at all or if you can skip the videos (like intro video) by pressing ESC for example or by just waiting.
5. Have you installed everything is necessary, that means PhysX for example if it needs it or is the right DX version used by CodeWeavers?

You were both right - it was a problem with physx being busted somehow when using CrossOver, but Gydion nailed it - wineskin worked like a charm. In the style of two worlds, Gentlemen, thou wert useful :D
Superedit: it didn't actually work - something about a missing sdbinst.exe. Oh well, I tried. Might give it a go properly later, but for now meh.

Unfortunately the GOG version of Two Worlds did not work out of the box for me too under Linux and Wine. Looks like there's some component missing in the installation.

I had played the German demo of Two Worlds before to test the compatibility with Wine and the demo worked. So I tried to install the GOG version into the same Wine tree where I had installed the demo. And inside of that tree the full version of the game works.

Maybe that works as a quick fix on the Mac too: Download and install the demo from www.2-worlds.com (with all components) and install the GOG version into the same Wine tree.

There's probably an easier solution. But I have bought Two Worlds just from the GOG birthday promo and hadn't have time to look into it more closely. And the motivation to do so isn't too high anymore now that the game runs. :)

Two Worlds requires PhysX; the GOG installer uses Nvidia's PhysX legacy installer whereas the demo uses the original Ageia installer. That would be why installing the demo fixed the problem. It should be possible to bypass the demo step by installing the last Ageia PhysX version under Wine.