Ruthless Returns

The developers describe how their game uses AI generated content like this:

Ruthless Returns is a solo-developed game built and refined over hundreds of hours. The original version was created on paper in 2022, but at the time I did not have the resources to turn it into a full game. Early prototypes used licensed images with a simple painted treatment. It worked, but the visual style was ultimately shaped by whatever suitable assets were available. Generative AI made it possible to create artwork specifically for Ruthless Returns and give the game a much more consistent look and feel from top to bottom. AI was used for the card artwork and character voices. That also made it possible for me to finally turn the original paper concept into a PC game. If players enjoy it, I hope to take it full circle and eventually produce Ruthless Returns as a physical board game. Balancing combines extensive human playtesting with more than 500,000 simulated games. The simulations were used to analyze win rates, card strength, strategies and interactions across a much larger number of matches than manual playtesting alone could realistically cover.

Required on Steam store pages since 2024. It covers content that ships in the game, on its store page or in its marketing — Valve does not require a disclosure for AI tools used during development, so this says nothing either way about how the game was made. Check it on Steam.