Stardew is always a good one and uses very little battery. Noita and Streets of Rogue have been fun too, and are also easy on the battery (pixel art roguelites).

I love the Deus Ex series and Human Revolution is worth checking out; even if you haven’t played the prior ones. It’s been a while since I played through it but I remember being drawn to the story and liked the stealth aspects.

The new System Shock remake is also great and is decent on my Steam Deck battery.