Like the Hyperion in Wings of Liberty, the Leviathan in HotS is the Zerg flagship where Kerrigan stays in between missions. From here, you can talk to various characters, access the Evolution Pit, and select abilities for Kerrigan to use. You can also access the archives and replay a previous mission. Unlike Wings of Liberty, the Leviathan is the only place where you’ll be in between missions. There is no bar or base camp on a planet where you can interact with objects and characters.
A new feature with Zerg is the ability to mutate and evolve in the campaign. Each of the seven main combat units has a choice between three mutations and two strains for evolution. Mutations improve units’ existing traits such as movement speed, armor, health, attack speed or range. These can be changed in between every mission.
Each unit has a choice between two strains for evolution. Before being able to choose a strain, the player must complete evolution missions. These are unlocked after certain levels in the campaign. An evolution mission is a set of two short missions that are designed to show the player the differences between the two strains. Think of it like a demo where the player can try them both before choosing. There are seven sets of evolution missions in total. After completing the evolution mission, the player can choose between two strains. Each strain alters the unit entirely. For example, one strain for Zerglings can make them jump cliffs and jump to enemies, while the other strain makes them almost spawn instantly when evolving from larvae. Some strains allow the unit to evolve into something different in real-time, such as the Hydralisk with a Lurker strain. The Hydralisk is evolved from larvae and then can be evolved into a Lurker which can attack while burrowed. These kinds of strains change the mechanics of the unit entirely. After selecting a strain, it cannot be changed during the course of the story. I haven’t went back to replay the game from the master archives, but it may be possible to change strains from there after finishing the game.
In HotS, Kerrigan can gain levels, which unlock new abilities. Unlike an RPG where players earn experience points from killing enemies, Kerrigan only gains levels from completing missions and bonus objectives. There are seven tiers of abilities to choose from. A new tier is unlocked after every 10 levels, with the exception of level 70. Level 70 is the maximum level, but the last tier of abilities is unlocked at level 60. Like mutations for regular units, the abilities for Kerrigan can also be changed in between every mission.
There are 20 main missions in total. Each mission has a strong focus on moving the story forward. The first few missions are pretty basic as they are designed to be tutorial levels, but it quickly ramps up. The gameplay itself is pretty much the same as Wings of Liberty, but with a different race, hero, and story. After certain levels, the player can choose which planet to travel to. Each planet has different units that are unlocked permanently after completing the mission. When compared to Wings of Liberty, the choice of which planet to go to first doesn’t seem to affect difficulty as much in later missions, but it might on brutal difficulty. There are also no missions that I remember where you must choose to do one objective or the other while in a mission. In Wings of Liberty, there were several missions where it was like this and it would affect the story. Also in Wings of Liberty were missions where your choices affected which units would be available in the last mission, but HotS didn’t have these choices and made it feel mostly linear.
Battle.net has been greatly improved over the years. For HotS, they added the ability to form groups and clans. These groups and clans can communicate in private channels to easily create or join matches together. Players can also play in any region while still using their native language. Replays are not only for watching anymore, but can also be used to resume play from a certain point. This even allows you to play from a reply from pro gamers. Another new feature is the leveling system in multiplayer and custom games. Spending resources and killing enemies will give experience points. You also get extra experience points for winning once per day per race. Gaining levels will unlock portraits, decals, dances, and skins.
HotS seemed a tiny bit weaker in terms of story than Wings of Liberty, but whenever a pre-rendered cinematic played, it made up for it. There aren’t any serious consequences to choices like in Wings of Liberty, and the missions felt more linear. Compared to normal difficulty between HotS and Wings of Liberty, HotS seemed easier. This might be due to the nature of Zerg and the new campaign features. For me, it was not as fun as Wings of Liberty, but that might be because I like playing as Terran more. There didn’t seem to be as many playable heroes and most missions required building units and bases. There weren’t as many of those one man army type of missions where you go through the mission with just your hero. Most of the missions were also timed in a way. My style is to take my time building a base, upgrading everything, and then sending my forces out, but timed missions don’t allow me to do that. Some missions contained some movie references, which were awesome, such as Harry Potter’s Priori Incantatem. Overall, if you’re a purist to the Wings of Liberty campaign, you might find HotS a little bit lacking, but if you’re a fan of the Zerg, you’ll love the new features and campaign.