A Fleet of Your Own: Tuning missions for persistent fleets

By Sacha Narine

The persistent fleet is a key feature of the Homeworld franchise and Homeworld: Deserts of Kharak. It provides the design team with great opportunities (and considerable challenges,) but its primary purpose is to give each player a unique and cohesive campaign experience. Each player starts with a handful of light vehicles and may expand and upgrade that small fleet in many different ways, carrying all vehicles and upgrades from one mission to the next.

In order to accommodate the persistent fleet, we needed a strong “dynamic difficulty” system, but we also needed to review many combat encounters to ensure they worked with various fleets on all difficulty settings.

As in the original Homeworld games, difficulty scales based on the size and value of your fleet. Whereas the earlier games increased enemy numbers, Deserts of Kharak changes the number of enemies as well as several other variables, including vehicle durability, encounter composition, enemy production times, and ability cool-downs. Some of these changes are handled by game-wide systems that detect the player’s fleet size and strength. However, much of this difficulty tuning was handled on a per-mission basis, requiring designers to script modifications to many encounters based on difficulty setting and fleet strength.

Players can start a mission with very different fleet compositions.

Two possible player fleets, upon entering Hell’s Gate early in the campaign.

A good example comes early in the campaign, as the player’s fleet enters “Hell’s Gate” in search of an ally. For this scenario’s first encounter, designer Michael Kuzel adjusted difficulty, hints and speech events to account for the player’s fleet before and after the encounter. Because this is the first encounter in Hell’s Gate, and the player has just acquired several new upgrades and abilities, we needed the encounter to provide a reasonable threat and allow some experimentation regardless of whether the player arrived with an armada of veteran vehicles or a handful of freshly produced light vehicles. On Classic difficulty, we ensure that the threat is significant regardless of the player’s fleet size.

Systems handle the scaling of vehicle statistics like durability, alert range, and weapon damage, but this scaling is dependent on the player’s chosen difficulty setting. When playing on Easy, enemies will scale up in power less dramatically than they do in Classic difficulty.

Once we had the campaign playable and fun on Normal difficulty, the design team was able to spend time adjusting mission scripts for Easy and Classic, accounting for the divergent strength of the player’s fleet. In many missions, we modified the number and type of enemies in several encounters, and in some situations we even swapped out encounters entirely or added new ones for Classic difficulty. However, these additional challenges still query the strength of the player’s fleet before initializing, ensuring that a player who is in serious trouble won’t be overwhelmed by additional threats.

A Gaalsien attack on the Khashar Plateau.

A Gaalsien attack on the Khashar Plateau.

Later in the campaign, while the player’s fleet fights to hold the Khashar Plateau, we made some small but significant adjustments to account for varying fleet compositions. We wanted to ensure that the player had static defenses available to defend the five choke points on the plateau. However, not all player fleets will include Baserunners with deployable turrets and mines. In addition, many players may not have purchased the upgrades available for the Baserunner and its tools. Without that vehicle and its upgrades, the player will not have access to strong enough defensive tools to hold the plateau.

Heavy turrets can help the player defend the Khashar Plateau, regardless of fleet composition.

Heavy turrets can help the player defend the Khashar Plateau, regardless of fleet composition.

To remedy this problem, we decided to grant the player several Heavy Turrets salvaged from their enemy in the previous mission. These turrets can hold out briefly on their own, but are extremely valuable when repaired and supported. They also vary in strength and quantity based on the player’s chosen difficulty setting.

Other variations to the Khashar scenario include the frequency and composition of enemy attacks, the composition of the final encounter, and how easily the player can halt enemy attacks by destroying Production Cruisers.

Assault vehicles and aircraft attack the plateau.

Here are some examples of fleet divergence that we expect to see when Deserts of Kharak goes live; Many players will appreciate the power of Railguns and their upgrades; it won’t be a surprise if these players amass a sizable squad of veteran Railguns. Other players will love the speed and power of airborne Strike Fighters, which are excellent at countering Railguns. These players will maintain a fully loaded hangar of upgraded aircraft.

Outside of a few tutorial moments, we never require the player to build a specific vehicle, and therefore we can’t know whether the player has Railguns, Strike Fighters, or any other vehicle apart from the two cornerstone vehicles of the Expedition. This means that players need several options for dealing with any encounter. While Light Attack Vehicles are often the most cost-effective way to defeat Railguns, aircraft can be equally effective if launched quickly. If the player has not acquired dedicated anti-air vehicles, several other vehicles can be upgraded with secondary anti-air weapons. If some poor misguided player chooses to forgo Support Cruisers, incredibly useful for resourcing and repair, then Science Office Rachel S’jet can step in to assist with repair duties.

A strong fleet holds ground on the plateau.

A strong fleet holds ground on the plateau.

The persistent fleet is a staple of the Homeworld franchise. More than any single vehicle or aircraft, it is the player’s avatar as they escape catastrophe and journey towards salvation. As a design team we often puzzled over how to accommodate all possible fleets and player skill levels, but in order to provide a personal experience to each player, we worked hard to craft a campaign that respects your choices and values your unique fleet.


  1. 1.
    I feel like im gonna play campaign 2nd time pretty soon because of persistence AND veterancy. Vet system in campaign is what boosts replayability greatly. With additional\side missions for main campaign you can provoke players to finish campaign over and over again with every patch.