Sony has been assuring us for a while that 99% of PS4 games will be backwards compatible on PS5. It turns out the actual figure is higher still.

On its online support page, Sony has revealed there are only ten PS4 games that won’t be playable  on the next-gen console. That’s from a total of more than 4,000 games released for the system, since its initial launch in 2013.
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https://www.trustedreviews.com/news/gaming/a-mere-10-ps4-games-wont-work-on-ps5-heres-the-list-4102985