Area Survivors

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

Generative AI tools were used during development to assist in creating some in-game visual assets, graphical assets, and store marketing artwork. All generated materials were selected, edited, adjusted, and reviewed by the developer before being included. The game does not use generative AI to generate content during gameplay.

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.