A recent survey by Google Cloud found that 90% of game developers are exploring generative AI. Millennium Whisper, a dating sim by Parable Studios, is the first game on Steam to run a large language model entirely on-device, avoiding cloud-based inference. This approach allows for unique in-game conversations and addresses ethical data usage, as actors retain ownership of their data and receive royalties. The game uses actor-led role-play sessions for character behavior, ensuring high-quality data. Running AI locally enhances energy efficiency and sustainability, contrasting with traditional server-based models that incur ongoing costs. Millennium Whisper received grant funding from Innovate UK and is currently in Early Access. Ambrose Robinson, the founder of Parable Studios, emphasizes the importance of energy savings and the sustainability of their AI approach.