And this was bound to happen. Despite the fact that Rockstead and Iron Galaxy have not released any patch to address the absence of AO in the PC version, some SweetFX mods appeared that do exactly that.
Now this can be considered as a temporary workaround and not a permanent solution, as we’re pretty sure that HBAO+ can look better than this (though it remains to be seen whether such AO will be used in the PC version).
Those interested can download the SweetFX mods that currently offer support for ambient occlusion from here.
And here is a comparison, showing AO in full action.