The only thing that comes to mind as far as gaming is PCVR. Games like No Mans Sky and MSFS struggle hard with even the 3090 Ti. The 4090 still can’t max graphics or resolution but it is a huge difference. Plus other PCVR titles are now able to play at 120hz refresh and/or high resolutions.

With the next gen PCVR headsets already here as well, and many many more around the corner, some will struggle to be used with even a 3080 on the lowest settings.

For desktop gaming though, very very few games.

But hopefully people are not buying the 4090 for just gaming. Hopefully they are purchasing for features such as the dual multiprocessor encoder, for the increase in energy effectiveness, for niche DLSS 3.0, using the huge increase in cuda for scientific research and purposes, for video editing/recording, for AV1, perhaps live streaming at high resolution, or a mix of all of the above with gaming.