The first Mistborn era seems like it would be perfect for a prequel game where you take part in the internecine house wars between the nobility. It would be an open world stealth/action super-power game. Great setting, the large sparling inspired city of Luthadel, a fusion of Victorian and gothic aesthetic. With blanketing ash from regular volcanic eruption and the ever-present mists at night. The crushing misery the nobles inflict on the Skaa (serfs) under the ever watchful eye of the immortal Lord Ruler and his inquisitors.

It would have unique gameplay mechanics. Burning iron and steel to push and pull off metal in structures to fly through the sky and over buildings. Pulling and pushing your enemies who are holding metal. Or deflecting/firing metal objects large and small at your enemies. Using pewter to make your character tougher, tin to enhance their senses. Use zinc and brass to sooth or riot enemies. So you can slip by them or you can make them panic and flee. Using copper to hide yourself from seekers and brass to detect other mistborns and mistings.

Likewise enemies would vary, from simple guards wearing metal armour and holding metal weapons (which they will abandon if you start pushing and pulling them for wooden clubs), to the more professional haze-killers with no metals on them and their wicker shields and dueling canes, to mistings who only have one of the 8 powers to use on you (coinshots who fire objects at your, lurchers who pull you, pewter arms who are extra tough, etc) to enemy mistborns who have all the same powers as you, then maybe at the end of the game you might even fight an inquisitor with their enhanced powers and gruesome metal spiked eyes.