I was recently thinking about a escape from tarkov/battle royale game mode, where all the players would fight for supplies.
The Idea was to make all the heroes with a more poorly look (like the E3 2016 trailer armors), and the same armors would change your gameplay stlyle, and be a counter to other heroes (like, equiping a more heavy armor for pk to be able to defend more propely sugoki attacks).
The gameplay of this 20 players game mode, could be like a more landscape cenario where you need to find supplies to survive and upgrade your armor, skill, weapon, etc. And the main goal will be Just to collect resources and kill bots/players that would be on the map, and If you be the last player alive you would gain extra loot/XP. Finally i would implement a death system that just delete all your progress (on this especific game mode), and a straction point to safe your inventory and leave, this would make you gain less XP/Loot than winning, but that would be a safest way to "Win".
Sorry if i wrote something wrong, i'm still learning english.