Setting: 10 years after the destruction of the UED fleet Kerrigan has monopolized the Koprulu Sector. The Terran are scattered and no longer united as the Dominion. The Protoss have built Shakuras into a homeworld rivaling Auir and send expeditions in search of other worlds with similar Xel'Naga structures that can protect them from the Zerg.
Heart of the Swarm: 18 mission campaign
Act 1: The Hunt for Mengsk
The player plays as Samir Duran, Kerrigan's right hand man. Kerrigan seeks revenge against Mengsk whose fleet she has twice destroyed, but the former rebel has proven to be resourceful. He has eluded Kerrigan for all these years, but now the Swarm has detected a large Terran military base on an outlying dwarf planet.
When the Swarm arrives in the system they are hailed by a Protoss mothership that informs them that the Zerg will be prevented from corrupting the Xel'naga artifact on the dwarf moon. After defeating the Protoss fleet hidden by the mothership the Swarm arrives at the walls of the base. Once Duran infiltrates and opens the gates the Zerg swarm in and overrun the fortification. Before the Zerg has a chance to fully search the base a Terran force deployed on the far side of the planet counterattacks. Their equipment has the Dominion emblem.
With the planet under full Zerg control Kerrigan and Duran tear the compound apart looking for Mengsk. Duran sees the Terran have modified the Xel'naga artifact is sending a great deal of energy into space. When he deactivates it an entire planet decloaks and Mengsk welcomes Kerrigan to New Korhal. A large Terran fleet orbits a thriving industrial world. They exchange death threats and the battle commences.
Kerrigan takes personal command of the Zerg forces engaged in the fleet battle and sends Duran on a secret mission to create a beachhead on the planet below. Landing alone on the outskirts of a city that contains a military base Duran slowly creates an army of infested terrans large enough to overrun the army base. Drop pods bring down some drones to start a Zerg base which Duran uses to besiege the main city. Mengsk of course has remote nuclear devices planted throughout the city which Duran can either disable or brute force through. As Duran surrounds the Mengsk compound Kerrigan lands on the planet and enters the compound with Duran. The compound is filled with traps and troops, and when they finally reach the deepest room Mengsk has already poisoned himself. In cinematic Kerrigan decapitates Mengsk and broadcasts herself to the remaining Terran worlds holding his head.
Act 2: The Prince
Kerrigan returns to Char and begins plotting a way to invade Shakuras because the Protoss remain the last threat to her power. Duran is left to his own devices, which means his hybrid experiments. He receives word from his brood on Aiur that they have unearthed a Dragoon factory filled with Protoss genetic material and data.
Before he arrives Zeratul has already begun leading an assault against his brood. To stand a chance against the Protoss onslaught Duran unveils the latest Zerg evolution unique to his brood, infestors. Having fought the battle to standstill both Duran and Zeratul enter the dragoon facility in a race to collect or destroy the resources within. After racing through the Protoss labyrinth the two meet and do battle. They wound each other and retreat with their respective spoils. Duran makes a last ditch attempt to prevent Zeratul's escape, but after crippling a large portion of his forces Zeratul still escapes.
Duran returns to Char where Kerrigan informs him of a strong Terran presence on Moria that she wants eliminated. This begins a three mission interlude playing as Terran. Duran sends a brood to the planet and begins encroaching on the Terran settlement. Duran arrives in the Terran settlement at the head of an elite mercenary commando team. The commandos successfully repel the Zerg attack destroying the spires leaving the brood grounded, and then the Terran begin to look skyward.
Duran and his team secure a space platform in orbit around the planet onto which they begin loading the planet's resources. Once the platform is secure Duran convinces the mercenaries to abandon the planet below and to keep the wealth for themselves which they agree to. Duran then goes back to the planet where he must disable the Terran defenses before several Zerg attack waves hit. In cinematic Duran decloaks in the security mainframe and watches as the Zerg over run the Terran defense forces after he disables the defense.
Act 3: Crossing Blades
Kerrigan congratulates Duran on eliminating the Terran and informs him that a large Protoss fleet has landed on Braxis. She tells Duran that she is removing the Zerg from there because the planet is worthless. Duran protests but won't tell Kerrigan why he values the planet. Instead he defies her orders and goes there himself. Duran begins evacuating his experiments immediately because Braxis was the center of his hybrid development. He successfully saves the most important of his specimens when Kerrigan arrives to discover his plans.
Duran and Kerrigan engage in a verbal confrontation where Duran says her services are no longer needed and that he is continuing the true work of the Overmind combining perfect essence with perfect form. Duran must defend against both the Protoss and Kerrigan who also fight each other.
When he defeats them he moves the lab he rescued from Braxis to the space platform around Moria. There he dispatches his mercenaries on Operation Falling Ash. If they complete this mission for him he promises them security in his new empire. Kerrigan assaults Duran's now infested platform as he begins to awaken his hybrid army. (These hybrids aren't the stupid Blizzard lightning tentacle beasts, but rather like zealots that hatch 2 in an egg with zergling speed or hydralisks with psi blades.) The main feature of the battle is Duran's infestors against Kerrigan's BW queens. Having spawned enough hybrids to win the battle Duran goes on the offensive.
Playing as the new hybrid race Duran wipes out Kerrigan's swarm on Korhal then moves on to Char. Duran intercepts Kerrigan on the outskirts of Char and as the battle rages in the air above the planet Duran begins detonating nuclear devices on the moons of Char. The moons hurtle into the planet smashing it into an unstable molten core. With her homeworld destroyed the Queen of Blades is defeated. Duran is confident that she is no longer a threat and let's her go. In cinematic Duran gives a monologue to an absent Kerrigan about the true purpose of the Zerg and Protoss. It shows shots of him opening a portal in deep space and something ominous emerging. It also shows Kerrigan arriving on Tarsonis with only a small force. She ends in exile.
I have thought up the main points of the LotV and WoL but haven't written those out in detail yet. Please give me your thoughts on my Zerg campaign.