The Heart of the Swarm campaign was also incredible. In the Zeratul missions the other players control a “Zeratul’s apprentice” unit with their own unique abilities. In missions where you play as Raynor, one person controls Jim while the other two people each get their own buffed up marine-like unit. In the Wings of Liberty campaign, for example, you get three different options for protoss and zerg research.
Not only have the maps been altered and the difficulty adjusted, but there are plenty of new upgrades, research options, mutations, etc. During this quarantine period my friends and I were messing around in the arcade and found a 3 player version of both the Wings of Liberty and Heart of the Swarm campaigns.