The opening to the level is perhaps what stayed the most consistent. I knew from the get-go that I wanted players to encounter the dead colony, defeat their attackers, then set up a base so that the level could truly begin.
It was important for me that I had the player come across the remains of the colony before getting in touch with the colonists so that the player knew the stakes (plus placing all of the wrecked vehicles, blood splatters, and carrion crows was too much fun). I did run into an issue of not allotting as much space between the beginning of the level, the dead colony, and the main base area as I would have liked, however I curved the path and created cliffs in order to artificially create more space.
Saving Ghosts, Disabling Towers
Initially, I intended for this level to take place much later in the game, which would have allowed players to create ghost units. When I discovered that the planet in which the level takes place was actually overrun by the Zerg in the first act of the game (something I had completely forgotten), those plans went out the door. Luckily this helped me with scoping, as I could boil down the level design to dealing with only a few various units.
With that said, however, that meant the player had to acquire ghosts somehow, and I didn't want to toss the tower-disabling mechanic. So instead I placed two ghosts out in the wild for players to find, and once uncovered, they would become a part of the player's army. Personally I found this to actually be more fun than if the player had been able to train their own ghosts. With only two available to them, players must be more conscious of the individual units health and energy levels. I slightly increased the health of the units so players wouldn't find their ghosts immediately destroyed after one slip up, but it is very possible for clumsy players to lose both ghosts and be forced into going in guns blazing.
As for the function of the ghosts themselves, it took my quite a while to figure out how to do the comm towers. Eventually I decided upon using sensor towers, which would disable the enemy's ability to attack the nearest colony if players hit them with a ghost's EMP round - something that turned out to be quite satisfying.
Colonies Under Attack
From the beginning I wanted there to be repercussions for players who attacked the bases without first disabling the comm towers, and I knew I wanted the colonies to be attacked. The issue I ran in to, however, were the details: how quickly would the enemy retaliate, how many units they would send, which units they would send, how many Confederate soldier units would be there to defend the colony, etc. This required a lot of tuning, and I'm still not quite sure I got it the way I want it. As it stands right now, the Confederate soldiers can fend off the Dominion long enough for the player to arrive (assuming the player reacts quickly and sends forces to aid them as soon as they're informed the Dominion are on their way).
Destroy Dominion Bases
Early on when I did my first scoping of the project, I reduced the number of bases from three to two. In addition to it working with the layout of the level better, two bases seemed like it would keep the player from feeling as though the objectives were too redundant.
Once that was decided, I got to learn firsthand that designing for an RTS can provide really unique problems that are quite time-consuming to test. For instance, if I place x amount of marines and x amount of marauders at the enemy base, how long will it take the average player to gather up the resources and construct the necessary units to be able to destroy those enemy units? I know about how many it would take, but how many players will guess incorrectly, then have to reconstruct their force after having it destroyed by the enemy? How will that added time affect the level? It's an odd problem to solve for, and I have to imagine that RTS developers such as Blizzard have formulas that they use rather than simple guess-and-check.
Escort the Colonists
For anybody that has read through my work in progress blog and saw the many "nothing new this week but triggers!" posts, this is where that time was spent. Originally not a part of the level, this objective was created some time in the early days of the project (I can't remember exactly when, but obviously it was a time when I was brimming with optimism). The old finale that I had intended relied heavily on the player using siege tanks and elevation to defeat the enemy in one final stand, however once siege tanks were out of the question it would no longer work (although I question if it would have ever worked).
The escorting of the colonists became the old objective's replacement, with the idea being this: each of the two colonies would send an APC from their colony towards the landing pad at the center of the map at once. Players would need to divide their forces in two in order to protect the APC's to their destination. Had I more time, I would have liked to have each convoy get attacked twice, with players having to alternate back and forth to ensure each APC was adequately protected. Instead, attack squads of Dominion units are sent out to meet each APC at approximate halfway points in their journeys.
All in all I think the objective works alright, but doesn't live up to the potential it could have. It appears (to me, anyway) that it's obvious in the layout of my level that this objective was not originally intended. The skirmishes between the convoy and the Dominion occur in rather claustrophobic areas, and paths that the APC's must take seem awkward at times. Unfortunately there was no way around this without completely redesigning the landscape, which with my time window wasn't a possibility.
Defend the Evac Zone
Even though I didn't have my big final stand that I had originally wanted, I did want to include a small one, at least. With the APC's in place, players have to defend the landing pad against Dominion forces before the APC's are willing to let the colonists out to run towards the ship waiting to take off. I designed this more as a victory lap for players rather than a true obstacle - the Dominion should be easily defeated by the player's remaining forces. I contemplated making it more difficult, however seeing as there was little time in between when the APC's are successfully escorted and when the final stand occurs, players wouldn't have time to create more units. If they lost the final stand, they wouldn't be able to react in time to prevent the destruction of the evacuation ship. I thought about giving players more time, but that seemed like it would mess with the flow of the level. Once the APC's are successfully escorted and the objective is right there in front of the player's eyes, it didn't seem right to make them wait for an extended period of time.
Once the Dominion is held off, player's are rewarded with a simple cutscene showing the colonists and Confederate soldiers getting into the evacuation ship and taking off. It's not much, but it sure was rewarding to create that at the end of a long project.