Players walk in to prefilled character sheets. Their characters are all peons in a battle that’s about to commence. Every time they die, they raise in rank and in level. They retain the memories they’ve gained while being other people and can choose which army to side with when they enter their next body.
I ran a Pathfinder game that basically functioned like a rouge lite. Every time you died you get to keep one piece of loot, a chunk of gold and some xp. The treasure was used to upgrade the starting town, adding merchants and temples ect. No story at all though just tons of dungeons.