Makes me think of the special Silent Hill ending where a dog was in a room pulling all the levers.

I imagine this concept as a rogue-like, the princess (player) loots the dragons stash and chooses power ups for each round and the order they apply (like super auto pets or Noita wands), then tosses them out to the approaching knight.

The dragon then sends goons in waves while the knight fights, getting power ups when the princess decides they need it. Essentially a tower defense game too. Or, with more player agency, the knight could also be controlled by the player, but making it a tower defense makes the player feel trapped as needed

Each Knight drops more loot for the dragons stash, increasing the mix of power ups and empowering the next knight even more.

It’s a bloody road of knights until the princess is rescued, then the player can be the next princess. In a different tower, with a different layout and starting stash.