I recently played a game that started at a specific level (Beginner) and within that level you could pass onto the next. Endlessly. Create a randomly generated instance of an area, that allows a group to fight until they wipe back to back. Every safe spot adds additional loot/shards, that are given once the group realize they cannot go further. When the vote is passed to end it, all members are moved to loot room and have the option of porting out like every mutation does after final boss.
Difficulty increases based on level.
Could be fun to see how far people can get.