I realize that HotS and LotV has a seven arcs structure where the missions can be roughly classified into the following order:
- Intro -> Char/Kaldir -> Zerus -> Stukov/Rescue Raynor -> Finale
- Intro-> Shakuras/Moebius -> Ulnar -> Taldarim/Purifier -> Finale
Here, Zerus and Ulnar are basically the turning point of the story (Kerri becomes primal queen and Artanis starts to gather more allies). These arcs are also what separate the two halves of the campaign in the sense that you cannot use units/tech unlocked in the 2nd half during the missions of the 1st half.
This way, we can also break the WoL missions into roughly 7 arcs:
- Intro -> Ariel/Tosh missions -> Horner/Artifact missions part 1 (Train Robbery, Cutthroat, Smash & Grab, The Dig) -> Horner/Artifact missions part 2 -> Finale.
Here, The Dig is the turning point of the campaign. It is the point where Raynor meets with Zeratul and gains more knowledge about the artifacts. Thus, it should be the mark halfway mark of the campaign. This way we won’t be able to bring Thor/BC into the fight against Selendis in Safe Haven.
For upgrade, give a certain amount of cash for each mission and let player choose how to buy unit upgrades or mercs that they have available up to that point.
For research, let player choose a certain number of upgrades across both zerg and protoss techs. The amount can be:
- 2-3 upgrades for the first missions of Ariel/Tosh/Tychus/Horner
- 3-5 for the second missions of Ariel/Tosh
- 5-7 for the second missions of Tychus/Horner, and the third missions of Ariel/Tosh
- 6-9 for the third missions of Tychus/Horner
- all 10 for the remaining
Honestly, something like this would be an awesome feature that can bring a refreshing change into a 9 year old game. However, I don’t know how hard it is to actually implement this.