The Floor Really is Lava
Taking its name from one of the most famous (and difficult) achievements in the game courtesy of Lucio, this game mode would have players not able to touch the floor. It would be a matter of insta-death because that would be too harsh. Still using some vertical maps there could be an Ovewatch elimination mode where being on the ground for too long would be deadly. Players would have to constantly be search for higher ground. This would lead to some very intense fights for territory even more when players are attacking or defending an objective.
This mode would be best served for those characters who can climb, fly or, in the case of Lucio, ride up the walls. Though conceivably it could be opened to every character if there are enough vertical structures on the map and there is a time limit to when the floor will “become lava.” It would force players to really find new and interesting ways to play and in its first year that has been one of the strengths of Overwatch’s new game modes.