I do not own Fallout. If I did, this is how I'd do it.
This is an elaboration of a plot mcguffin that I felt deserved to be posted alongside the Act.
Fallout: Orleans
Campaign Act 2: The Orleans Offensive
With the discovery of the Bayou Cure, the Navigator has introduced a new variable and catalyst that will reshape the conflict. With long-term impacts of the Cure expected to be decisive in terms of gathering support and influence for the holder, all the factions understand that the status-quo of the last several years is ending. The faction without the Cure will have to pursue a victory in the near-term before the Cure starts bearing fruit, while the faction with the Cure will have to withstand the upcoming assault.
As both the Enclave and Orleans begin to mobilize for a major battle, the Blue Waters are making their own preparations. With the quagmire changing to a decisive battle, the Blue Waters will have to leave the region soon, and quickly. Preparations are underway for everyone as an escalation of violence is imminent.
During this time, the Navigator has a reputation but is uncommitted. By the end of Act 2, this will change, and enemies will be made. Until that point, the Navigator still has to recover their boat from the Blue Waters and decide who they will support.
As the Navigator deliberates, storm clouds gather. Hurricane season is upon the city, the traditional season for major battles in this war…
Act 2's focus is-
-Tentative faction alignment between Enclave and Orleans. When the Navigator finishes Act 1, it's likely with a strong factional leaning one way or another. With the pardon and approval bonus guaranteeing at least one of the factions feels warmly towards the player, reaching out to the other power of the Enclave/Orleans duality requires deliberate effort by the player in order to change alignments. If the player doesn't wish to change sides, however, they can begin the climax mission (choosing between Enclave and Orleans) as soon as they recover their boat.
-Meeting the Blue Water Pirates. Recovering your boat is a story requirement, and it happens to be inside the Pirate Cove. If the player hasn't already done the quest to gain access, they player has to do so now, and in doing so meets Captain Supermutant, leader of the Blue Water Pirates, for the first time. The player gains the opportunity to begin working for the Blue Waters. Siding with the Blue Waters isn't settled in Act 2, but players can begin doing so now.
-Gaining access to Pirate Cove to get the boat may require help from Enclave and Orleans territory. The player may be guided to visit both capital sections in the city in order to figure out how to get entrance to Pirate Cove. This lead-in guides the player to encounter city leadership from the rival factions. This is not necessarily a requirement.
-Widespread exploration and side quests. With the recovery of the player's boat and the Cure, far more of the map is opened up the player: the boat not only enables speed of travel, but allows you to go far deeper into the Bayou and off the coast far more easily than the player could before. Now is an ideal period for continuing exploration and sidequests, in order to build up factional alignment.
-Final factional alignment (Enclave vs. Orleans). Once the player has recovered their boat, they can begin the climax of Act 2. The player chooses which faction they will support. The climax of Act 2 is mutually exclusive between the Enclave and Orleans, and guarantees factional alignment between the two by removing one of them from the end-game options.
Act 2's climax is-
-The Orleans Empire is seeking to launch a major offensive against the Enclave, either to capitalize on their possession of the Cure or to demonstrate their strength despite lacking it. The Navigator is hired to carry soldiers across the Mighty Mississippi, either Orleans attackers or Enclave reinforcements, and winds up in the fray.
-The offensive is timed to correspond with a hurricane hitting the coast, a period at which Enclave technology is most limited. The strategy is a high risk, high reward strategy that has both been successful and failed Orleans in the past.
-The culmination of the battle is an Enclave counter-attack over the Projector, the symbol of controlling the heart of the city. The Enclave has been expecting a Hurricane offensive, and long been planning its counter-attack.
Act 2's Big Choices is-
-Determining who holds control of the Projector at the end of the battle. Whoever won the battle has gained a significant upper-hand in the war for the city, making significant gains across the city and in the disputed territories. Consequences are the shaping of the end-game, the epilogue, and a cementing of factional alignments between Enclave/Orleans into Act 3.
-Betrayal of the faction you started with IS possible. You can sabotage the counter-attack or betray the defenses of the Projector if you so choose, and thus side with the other faction. Doing so gains you extra caps and approval, but no pardon and no forgiveness for past crimes.
-The mission ends with a two-week time skip as the aftermath of the battle and storm is felt. Changes around the city include the changeover of disputed territories, ambient conversations, newspaper articles, and the Projector-radio reflecting whoever is holding it.
Author Note:
Act 2's climax is a major battle in the center of the city, making it a cross between the Battle for Hoover Dam and FO3's liberation of the aqua purifier. No giant robots, but most of the combat can be handled by NPCs. The player can be involved in the fight, or just concentrate on running forces from one shore to the next. Getting upgrades for the boat, like increased armor, makes the mission much easier.
Act 2 is the portion of the game players are expected to spend the most time in, while being the potentially shortest of the main story acts. In theory the act could be as short as traveling from the Act 1 climax drop-off point, going to the Blue Waters base, and then signing up for the climax battle. While players would need to regain reputation with the faction they sided against in Act 1's climax, there is no equivalent for the FNV arc of visiting and recruiting almost all of the Wasteland's minor factions. The closest there is the Act 3 factional end-games, where the player is tasked to go across the wasteland to resolve things in the faction's favor.
This is because I consider FNV's extremely long mid-game a weakness to the overall tension of the war buildup. As the elite NCR Rangers and Legion forces would only become common late into the end-game after you addressed most the minor factions, I wanted the opportunity to race towards the end-game for players who were interested in accelerating the plot and the end-game world state. The Act 2 climax serves more like the arrival of the Enclave in FO3, a player-controlled transition between mid and end game that changes the status quo and increase the world map's danger level as new and dangerous troops come to the field.
One one hand, this makes the critical path shorter. On the other hand, is that such a bad thing? While Act 2 could use a modest sequence to help channel exploration in and among the city of Orleans, possibly requiring visits to the three main factions in order to get access to the Blue Water base, the phase of 'contacting major settlements of the Bayou' would really fall in the Act 3 buildup to the finale. The only minor faction I could see as warranting a mandatory Act 2 contact is the Hidden Village, for some mcguffin to get to the Blue Waters base and serving as a recruitment of an ally for your eventual faction, but that's it.
Secret of the Bayou:
The major military forces of Orleans change over the Acts.
In Act 1, everyone is on the general status quo footing of a low-intensity conflict with fewer and smaller clashes. Orleans is dependent on militia, the Enclave relies on locally recruited security forces with power armor only at certain facilities, and the Blue Waters just have raiders and weak mercenaries.
In Act 2, mid-tier forces are being mobilized for the upcoming major battle. The Act 2 climax takes place during a stormy day during Hurricane Season. Hurricane Season is a historic time for Orleans offenses against the Enclave, to take advantage of the weather restricting Enclave technology. Orleans is fielding more and more Veterans, the Enclave mixes in power armor army troops with more combat-worthy guards, and the Blue Waters break out Talon Company. Come the finale you're seeing the major combat forces in play.
In Act 3, everyone is preparing for the end-game and breaking out their elite forces for the decisive finale. Orleans deploys the Royal Guard, the Enclave brings in its heavies and inferno troopers, and the Blue Waters deploy Supermutant Pirates.