I never build a game in the workshop before so I am just throwing this idea out there.
It is a game mode that plays random king of the hill maps. Whenever a team loses a round, the losing team votes for a player in the team to choose an upgrade to one of the hero’s skills. Each player can change their vote until there is a majority (The specific power-up choices can be those cool power-ups in the overwatch 2 PvE or whatever is fun and powerful. The upgrade is applied to a hero for the whole team. It means that the other players in the team can switch to that hero later and still use that upgrade.) And in the next round if the other team loses, they can upgrade one of their hero’s skill as well.
And maybe more than 3 rounds for that game mode will be fun? More round = more interesting combination of upgrades