Opposite Day

all your actions have a very opposite, inequal reaction
shooting an opponent damages you instead and heals your enemy
trying to heal yourself also damages yourself
character's healths are inverse order as well: tracer has the most health and wrecking ball has the least amount
gain points by killing yourself
(environmental deaths will still count against your score and there's no self damage)

(stuns and boops are also (kind of) reversed)