Horny Waifu: Kaiju Strike

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

All game content, including 3D models and 2D illustrations/animations, is originally designed and handcrafted by our artists. However, we use AI tools during early prototyping stages to explore angles, compositions, or ideas that help speed up the creation process. No live-generated AI content is used.

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.