Renegade Roundup is a new battle mode in Mario Kart 8 Deluxe.
The mode is part of the Battle Mode. In this mode, the players are split into two teams. The authority uses piranha plants to attack and capture the other team, the renegades. When a renegade is attacked by an authority's piranha plant, they will be sent to a cage on various points of the map. Free renegades can allow their captured allies back into the game by flipping the key switches under the cages.
The authority wins by capturing all the renegades before the time runs out, while the renegades win if any renegades are free when time runs out.
This battle mode's rules are very similar to Cops n' Robbers.