In this mode crouching next to a teammate will allow you to merge with them. Merged heroes are controlled by all the players merged with them and have all of the abilities of the heroes merged with them, but only appear as one hero. When merged with another hero using an ability or attacking reveals your hero in the merged hero for a few seconds in the form of a hero icon.
The hero that your merged hero appears as is the base of the merged hero. This player controls the basic movement of the merged hero and the merge will separate if they die. When merging, the player who crouched to start the merge will be merged into the other hero, the player who didn't crouch is always the base hero for the merge. Any number of heroes can be merged into a single merged hero in this mode.
Crowd controls such as stuns or hack will apply to everyone in the merged hero. Sombra's stealth will also be interrupted if anyone in the merged hero attacks or uses an ability. Most movement abilities will work while merged with a few exceptions that are difficult to detect such as Hanzo's Lunge and Brigitte's Shield Bash that may be added in the future. Holding interact for 1 second while not merged with anyone will disable merged movement abilities in case someone thinks it's funny to blink you off the map every time you spawn.
If the camera bugs pressing interact will fix it. Players merged with other heroes are in 3rd person, because the 1st person camera is blocked by the visible base hero. The 3rd person reticle is accurate in this mode. You can use the partially blocked 1st person camera by holding interact. Pressing interact without holding it will change the camera back.
It sounds a little complicated with this description, but it really isn't. Just walk over to the nearest teammate and crouch at them until something happens. It's fairly intuitive once you see it working.
This game has lots of Workshop settings. Most of them are available in the Workshop settings menu! The game will try to explain all the settings that are enabled when players first join. This gamemode is also compatible with most event gamemodes that support the Workshop!