As for the main subject of this topic, I've been working on the story (mostly from canon sources, such as the original SC campaign, and Starcraft: The Queen Of Blades) and design for a Protoss precursor campaign, detailing Tassadar's side of the Terran and Zerg campaigns, starting with the infestation of Chau Sara, and ending with Protoss campaign mission 4.
These, most likely, will have both one-player and two-player versions. For the two-player versions, both players will likely have the same color, blue. At the moment, I'm still trying to devise gameplay ideas for most of the missions, since I have very few actual ideas to make things interesting.
Canon-status sources: SC campaign (just put on cheats and play through), http://starcraft.wikia.com/wiki/Tassadar, http://starcraft.wikia.com/wiki/Edmund_Duke, Starcraft: Queen of Blades novel by Aaron Rosenburg.
Spoiler
P1)Invasion of Chau Sara
Description: With an infestation discovered on Chau Sara, Tassadar has ordered a small strike force to go to the surface, and determine the extent of the infestation, and if possible, eradicate it.
Forces: Expiditionary Force (Blue), Zerg Swarm (Purple)
Comment: Fairly story friendly. They never said they -didn't- land on the planet first.
Gameplay: Probably the standard "You have troops, carve out a main, then set one up" scenarios. Should be Terran mission 7 level difficulty, to start the player(s) off.
2P: Second player starts with units and probes, too.
//Chau Sara gets sterilized
P2)No name yet
Description: Breaking through the Zerg in orbit around Mar Sara, at the end you get confronted by General Duke and a pretty fair armada.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange), Terran Confederacy (White)
Comment: Meh, I didn't want NOTHING in between Chau Sara and Mar Sara, and Duke's valiant, though pathetic, stand was too big to leave out.
Gameplay: No ideas, but you have access to capitol ships.
2P: Another base.
//They move on to Mar Sara
P3)Infection
Description: Tassadar personally attends the scouting force to the surface of Mar Sara, to determine if the planet is rescuable.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange), Confederacy? (White)
Comment: I think it was in a book, but he did join in on a scouting force to Mar Sara. He burns it afterward and moves on to Antiga Prime. I'd like to incorporate Fire Base Chimera (http://starcraft.wikia.com/wiki/Fire_Base_Chimera), as well.
Gameplay: With Fire Base Chimera, it'll probably be a "Get to the Terran base before the timer", then reinforce it. In the two-player map, one will control the Protoss base, while the second will control Tassadar, a few other units, and the Terran base once you get it. Of course, that's not incredibly canon, so it might be an "assault the infested terran base" map, which is more boring.
2P: "Get to the base before the timer": One will control the Protoss base, while the second will control Tassadar, a few other units, and the Terran base once you get it. "Assault the infested terran base": Second player has a base.
//They burn Mar Sara and move on to Antiga Prime
P4)Valiance
Description: Before retreating, the Sons of Korhal attack the largest Hive Cluster on the planet. Vastly outnumbered, they deal decent damage, but come under massive attack. Tassadar, however, arrives and reinforces them.
Forces: Expiditionary Force (Blue), Sons Of Korhal (Red), Zerg Swarm (Orange)
Comment: Protoss' point of view on the hidden mission 'Biting The Bullet', which was cut from the original campaign.
Gameplay: I suppose you arrive with units, set up a base, and help the Terran computer take out the Zerg base.
2P: Second player sets up a base, as well.
//After that, The Sons of Korhal retreat (This is between Terran 7 and
and Delta Squadron is left behind to deal with the Zerg and the general population
P5)Antiga's Fall
Description: Tassadar joins forces with Delta Squadron to try to evacuate Terrans from Antiga Prime.
Forces: Expiditionary Force (Blue), Terran Confederacy (Orange), Zerg Swarm (Purple)
Comment: Again, I think it was in a book. Delta Squadron was defeated by the Zerg while trying to evacuate the population, after the Sons of Korhal broke through the Confederate blockade. After that, Tassadar decided to burn what was left of the planet.
Gameplay: Player(s) have an ally, for this match (Orange Terran). I think some time-based objective, like defending the Terran player for a little while. After the timer, some dropships come under attack from scourge and mutalisks, killing the evacuees.
2P: Second player has a base, but it's not as established.
//They burn Antiga Prime, and move on to Tarsonis. This mission is concurrent with Terran 9
P6)All Out War
Description: Tassadar attempts to get through the Zerg and Confederate force in orbit, to attack the Hive Clusters.
Forces: Expiditionary Force (Blue), Terran Confederacy (Brown), Zerg Swarm (Purple), Sons Of Korhal? (Red)
Comment: The mission itself will probably be during Terran mission 9. In the briefing, Tassadar'll have a short conversation/argument with Kerrigan. Tassadar said during the briefing in Zerg 6 that he and Kerrigan had met before, so this is probably that occasion (in the briefing).
Gameplay: Destroy all enemies! Massive free for all between the Zerg, Confederacy, Protoss and maybe the Sons of Korhal. Again the player has access to the big ships, the Zerg has fewer limitations (probably no Defilers or Spawn Broodling), and the Terrans have ghosts, but no nukes.
P2: Second player has his own base on an island that's not as established.
P7)The Battle of Tarsonis
Description: Tassadar sends a force to destroy the primary Zerg Hive Cluster the old-fashioned way. Meanwhile, remnants of the Confederacy struggle to survive.
Forces: Expiditionary Force (Blue), Zerg Swarm (purple and maybe orange), Terran Confederacy (Brown)
Comment: This should definately be in, since the advisor in the briefing for Terran 10 said that the Protoss and Zerg were still battling on the surface.
Gameplay: The only easy expansions would be by destroying one or two of the weak brown Terran bases. Then you'd have the resources to defeat the Zerg forces. However, attacking them would make them become hostile to you (now that'd be a tricky condition, but the action part is easy. I wonder if the AI scripts will attack the player's an enemy, though, when that's changed in-game).
2P: Second player has a base.
//Since Tassadar didn't just wipe the infested worlds to begin with, as he was ordered, Aldaris (who acted an an advisor for the whole campaign, thus far), orders Tassadar to return to Aiur. Tassadar refuses, so Aldaris takes the majority of the fleet (and the Gantrithor) back to Aiur. Tassadar takes another Carrier, the Altera, as his flagship.
P8)Summons
Description: Tassadar comes to Char to investigate that psionic distress call from Kerrigan (Zerg 3/4). Before he can do that, he must destroy the almost-infested ships in orbit.
Forces: Expiditionary Force (Blue), Zerg Swarm (Red and Orange), Terran Dominion (White)
Comment: When his fleet came to Char, he had to destroy what's left of Raynor's and Duke's fleet to keep them from being infested.
Gameplay: Again, a full ship map, though from here on, you don't have Arbiters (They're Judicator-controlled and Aldaris took most of the fleet back to Aiur). You have a certain time limit to destroy the scattered battlecruisers defended by Zerg.
2P: Second player, again, has a base.
P9)Reunion
Description: Tassadar sets up a base camp on Char, where he meets the Dark Templar.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange and maybe Purple), Zeratul's Warband (Brown)
Gameplay: Set up a base with Tassadar, some units and some workers. When you set up a Nexus, the Dark Templar'll appear. After a fairly good-sized cutscene, Raynor appears and points out the Zerg moving in to attack. After that, the objective is to take out these Hive Clusters to allow you to retreat and set up a camp elsewhere, undetected. This mission will be fairly reminiscent of BW Protoss mission 2 "The Dunes Of Shakuras."
2P: Not sure. Either as the Terrans, if they're included, or more Protoss.
P10)Immortality's End
Description: Tassadar and Zeratul devise a way to defeat one of the Zerg Broods on Char. With
Tassadar keeping Kerrigan busy, Zeratul's force will penetrate the Garm Brood's defenses and kill it's Cerebrate.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange (two or three of them) )
Gameplay: Similar to Protoss 9, where you have to get Zeratul to kill two cerebrates.
Possibly, the player could sneak Zeratul and some Dark Templar in to kill Zasz (with a small battle with zerglings and hydralisks, during). Then, a massive battle between various facions of the brood (to make it look like it's going haywire). The base-managing player might have to get in to rescue Zeratul, afterward.
2P: Second player will probably control Zeratul and maybe a second base.
//Kerrigan hits and destroys the main Protoss base camp on Char.
P11)Hunted
Description: Tassadar and Zeratul's force being hunted by Kerrigan, after Zerg 8.
Comments: Not really many ideas. From what I understand, between Zerg 8 and Protoss 4, the remaining Dark Templar and what was left of Tassadar's force was being chased around by Kerrigan. Also, how would the Dark Templar get seperated from Tassadar's force?
Forces: Expiditionary Force (Blue), Zerg Swarm (Purple (two or three) )
Gameplay: *Shrugs*
P12)Inevitability
Description: Tassadar's force on Char Aleph against Daggoth's Tiamat Brood.
Comments: Nothing really to comment on.
Forces: Expiditionary Force (Blue), Zerg Swarm (Red (two or three)).
Gameplay: Either a 'hold out through the timer' or a 'take out the Zerg' map.
Description: With an infestation discovered on Chau Sara, Tassadar has ordered a small strike force to go to the surface, and determine the extent of the infestation, and if possible, eradicate it.
Forces: Expiditionary Force (Blue), Zerg Swarm (Purple)
Comment: Fairly story friendly. They never said they -didn't- land on the planet first.
Gameplay: Probably the standard "You have troops, carve out a main, then set one up" scenarios. Should be Terran mission 7 level difficulty, to start the player(s) off.
2P: Second player starts with units and probes, too.
//Chau Sara gets sterilized
P2)No name yet
Description: Breaking through the Zerg in orbit around Mar Sara, at the end you get confronted by General Duke and a pretty fair armada.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange), Terran Confederacy (White)
Comment: Meh, I didn't want NOTHING in between Chau Sara and Mar Sara, and Duke's valiant, though pathetic, stand was too big to leave out.
Gameplay: No ideas, but you have access to capitol ships.
2P: Another base.
//They move on to Mar Sara
P3)Infection
Description: Tassadar personally attends the scouting force to the surface of Mar Sara, to determine if the planet is rescuable.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange), Confederacy? (White)
Comment: I think it was in a book, but he did join in on a scouting force to Mar Sara. He burns it afterward and moves on to Antiga Prime. I'd like to incorporate Fire Base Chimera (http://starcraft.wikia.com/wiki/Fire_Base_Chimera), as well.
Gameplay: With Fire Base Chimera, it'll probably be a "Get to the Terran base before the timer", then reinforce it. In the two-player map, one will control the Protoss base, while the second will control Tassadar, a few other units, and the Terran base once you get it. Of course, that's not incredibly canon, so it might be an "assault the infested terran base" map, which is more boring.
2P: "Get to the base before the timer": One will control the Protoss base, while the second will control Tassadar, a few other units, and the Terran base once you get it. "Assault the infested terran base": Second player has a base.
//They burn Mar Sara and move on to Antiga Prime
P4)Valiance
Description: Before retreating, the Sons of Korhal attack the largest Hive Cluster on the planet. Vastly outnumbered, they deal decent damage, but come under massive attack. Tassadar, however, arrives and reinforces them.
Forces: Expiditionary Force (Blue), Sons Of Korhal (Red), Zerg Swarm (Orange)
Comment: Protoss' point of view on the hidden mission 'Biting The Bullet', which was cut from the original campaign.
Gameplay: I suppose you arrive with units, set up a base, and help the Terran computer take out the Zerg base.
2P: Second player sets up a base, as well.
//After that, The Sons of Korhal retreat (This is between Terran 7 and

P5)Antiga's Fall
Description: Tassadar joins forces with Delta Squadron to try to evacuate Terrans from Antiga Prime.
Forces: Expiditionary Force (Blue), Terran Confederacy (Orange), Zerg Swarm (Purple)
Comment: Again, I think it was in a book. Delta Squadron was defeated by the Zerg while trying to evacuate the population, after the Sons of Korhal broke through the Confederate blockade. After that, Tassadar decided to burn what was left of the planet.
Gameplay: Player(s) have an ally, for this match (Orange Terran). I think some time-based objective, like defending the Terran player for a little while. After the timer, some dropships come under attack from scourge and mutalisks, killing the evacuees.
2P: Second player has a base, but it's not as established.
//They burn Antiga Prime, and move on to Tarsonis. This mission is concurrent with Terran 9
P6)All Out War
Description: Tassadar attempts to get through the Zerg and Confederate force in orbit, to attack the Hive Clusters.
Forces: Expiditionary Force (Blue), Terran Confederacy (Brown), Zerg Swarm (Purple), Sons Of Korhal? (Red)
Comment: The mission itself will probably be during Terran mission 9. In the briefing, Tassadar'll have a short conversation/argument with Kerrigan. Tassadar said during the briefing in Zerg 6 that he and Kerrigan had met before, so this is probably that occasion (in the briefing).
Gameplay: Destroy all enemies! Massive free for all between the Zerg, Confederacy, Protoss and maybe the Sons of Korhal. Again the player has access to the big ships, the Zerg has fewer limitations (probably no Defilers or Spawn Broodling), and the Terrans have ghosts, but no nukes.
P2: Second player has his own base on an island that's not as established.
P7)The Battle of Tarsonis
Description: Tassadar sends a force to destroy the primary Zerg Hive Cluster the old-fashioned way. Meanwhile, remnants of the Confederacy struggle to survive.
Forces: Expiditionary Force (Blue), Zerg Swarm (purple and maybe orange), Terran Confederacy (Brown)
Comment: This should definately be in, since the advisor in the briefing for Terran 10 said that the Protoss and Zerg were still battling on the surface.
Gameplay: The only easy expansions would be by destroying one or two of the weak brown Terran bases. Then you'd have the resources to defeat the Zerg forces. However, attacking them would make them become hostile to you (now that'd be a tricky condition, but the action part is easy. I wonder if the AI scripts will attack the player's an enemy, though, when that's changed in-game).
2P: Second player has a base.
//Since Tassadar didn't just wipe the infested worlds to begin with, as he was ordered, Aldaris (who acted an an advisor for the whole campaign, thus far), orders Tassadar to return to Aiur. Tassadar refuses, so Aldaris takes the majority of the fleet (and the Gantrithor) back to Aiur. Tassadar takes another Carrier, the Altera, as his flagship.
P8)Summons
Description: Tassadar comes to Char to investigate that psionic distress call from Kerrigan (Zerg 3/4). Before he can do that, he must destroy the almost-infested ships in orbit.
Forces: Expiditionary Force (Blue), Zerg Swarm (Red and Orange), Terran Dominion (White)
Comment: When his fleet came to Char, he had to destroy what's left of Raynor's and Duke's fleet to keep them from being infested.
Gameplay: Again, a full ship map, though from here on, you don't have Arbiters (They're Judicator-controlled and Aldaris took most of the fleet back to Aiur). You have a certain time limit to destroy the scattered battlecruisers defended by Zerg.
2P: Second player, again, has a base.
P9)Reunion
Description: Tassadar sets up a base camp on Char, where he meets the Dark Templar.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange and maybe Purple), Zeratul's Warband (Brown)
Gameplay: Set up a base with Tassadar, some units and some workers. When you set up a Nexus, the Dark Templar'll appear. After a fairly good-sized cutscene, Raynor appears and points out the Zerg moving in to attack. After that, the objective is to take out these Hive Clusters to allow you to retreat and set up a camp elsewhere, undetected. This mission will be fairly reminiscent of BW Protoss mission 2 "The Dunes Of Shakuras."
2P: Not sure. Either as the Terrans, if they're included, or more Protoss.
P10)Immortality's End
Description: Tassadar and Zeratul devise a way to defeat one of the Zerg Broods on Char. With
Tassadar keeping Kerrigan busy, Zeratul's force will penetrate the Garm Brood's defenses and kill it's Cerebrate.
Forces: Expiditionary Force (Blue), Zerg Swarm (Orange (two or three of them) )
Gameplay: Similar to Protoss 9, where you have to get Zeratul to kill two cerebrates.
Possibly, the player could sneak Zeratul and some Dark Templar in to kill Zasz (with a small battle with zerglings and hydralisks, during). Then, a massive battle between various facions of the brood (to make it look like it's going haywire). The base-managing player might have to get in to rescue Zeratul, afterward.
2P: Second player will probably control Zeratul and maybe a second base.
//Kerrigan hits and destroys the main Protoss base camp on Char.
P11)Hunted
Description: Tassadar and Zeratul's force being hunted by Kerrigan, after Zerg 8.
Comments: Not really many ideas. From what I understand, between Zerg 8 and Protoss 4, the remaining Dark Templar and what was left of Tassadar's force was being chased around by Kerrigan. Also, how would the Dark Templar get seperated from Tassadar's force?
Forces: Expiditionary Force (Blue), Zerg Swarm (Purple (two or three) )
Gameplay: *Shrugs*
P12)Inevitability
Description: Tassadar's force on Char Aleph against Daggoth's Tiamat Brood.
Comments: Nothing really to comment on.
Forces: Expiditionary Force (Blue), Zerg Swarm (Red (two or three)).
Gameplay: Either a 'hold out through the timer' or a 'take out the Zerg' map.