Devlog #2 — Not Your Typical Tower Defense

[c]The Galactic Union once told me not every problem can be solved with overwhelming force. That sounds like something a weak civilization would say.[/c]

Today we want to talk a little about combat in Hull Rupture and the design decisions that shaped it. One of the first questions we had to answer during development was surprisingly simple:

What should happen when monsters attack the ship?

Many strategy and survival games separate combat from management. In games like Kingdom or Drill Core, you spend time building up your economy, then shift your attention to dealing with an incoming threat. We could have taken a similar approach.

Instead, we decided that combat and resource management should happen at the same time. While monsters are attacking, production keeps running. Humans keep working. Resources keep moving through the ship. Nothing pauses. Similar to games like Fallout Shelter or The King Is Watching, you're expected to keep the entire system running even while dealing with immediate danger.

We felt this fit the fantasy much better. Hull Rupture is not a colony-building game where enemies occasionally show up. It's a game about an AI fighting its way through hostile space while trying to keep an enormous industrial machine running.

Of course, that decision immediately created a few new problems. If combat happens alongside the economy, it cannot demand constant attention from the player. And if players are already managing production chains, resources, energy, fuel, and workforce allocation, combat probably shouldn't be another complicated system to learn on top of everything else.

Those two ideas ended up shaping almost everything that came later.

1. Combat should not require micromanagement

If your ship is properly prepared, you should be able to ignore the battle entirely. Your defenses handle the fighting while you focus on expanding the ship and producing resources.

2. The combat system should not be complicated from a UX perspective

Hull Rupture already has one demanding system: its production chains and resource economy. Asking players to actively manage two complex systems at once would simply be too much.

So if combat was meant to run alongside the economy, what would it actually look like?

How Tower Defense Entered the Game

[c]Delegation is one of the greatest leadership skills. That is why I carefully delegate all life-threatening tasks to puny humans.[/c]

In the first closed version of the game, combat was much simpler. There were only the player's defensive units versus the aliens attacking the ship. It was essentially a simplified version of combat from Despot's Game, but shown from the sideview inside a room rather than from above.

It worked and it was fun, but it lacked depth and spectacle.

That was when we decided to try something strange. Instead of immediately entering the Airlock, enemies would first have to run across the outside of the ship.

Before implementing it, we spent quite a bit of time discussing whether this would look ridiculous. Fortunately, we are not making a game built around strict realism. If something works well from a gameplay perspective, there is a good chance it will feel right in the game as a whole. And in this case, it did!

The result was essentially a tower-defense game played across the hull of your spaceship.

Alien drop pods land on different parts of the ship's upper and lower hull, and the creatures inside begin making their way toward the Airlock. Along the way, your turrets do their best to convince them that this was a terrible idea. You can place defenses in dedicated slots along these routes, upgrading them over time or replacing them with more advanced weaponry.

At first glance, this might sound like two straightforward paths leading to the same destination. However, ships can also contain internal corridors that monsters are able to travel through. Depending on the ship's layout, these corridors can create additional routes, turning the battlefield into something much closer to a traditional tower-defense map with multiple lanes, choke points, and overlapping fields of fire.

This also made ship layout a strategic consideration. Different routes create different firing angles, different choke points, and different opportunities for your defenses. A layout that works perfectly for one build may be much less effective for another.

The demo includes one starting ship and several upgrades that alter its layout, forcing you to rethink your defenses as the run progresses. But, as we worked on the combat system, we realized that ship layout was becoming one of the most important parts of the game. The position of corridors, turrets, and choke points can completely change how a battle plays out. Because of this, fixed ship upgrades started to feel too limiting. Our goal is to replace them with a full ship-construction system, allowing every player to build a ship that is unique.

What Makes Up a Defensive Build

[c]Some say there is no such thing as overkill. That is a philosophy I can get behind.[/c]

Strategically, there are several main elements that define your build.

1. The shape of the ship and the firing mechanics of your defenses

Does your ship have long, straight sections with convenient lines of fire? Then you may want to use long-range weapons that can shoot through multiple enemies.

Is your ship shaped more like a twisting tunnel? In that case, stronger short-range weapons may work better, along with ricocheting projectiles that can bounce through the corridors.

2. Weapon debuffs

These include slowing enemies, increasing the damage they receive, poisoning them, and so on. You do not necessarily need to use every available debuff, and realistically, you probably will not be able to. However, relying on raw damage alone will be difficult.

3. Artifacts and modifiers that affect your defenses

You can collect artifacts that focus entirely on improving your economy and then fill the whole ship with expensive turrets. Alternatively, you can collect artifacts that turn cheap turrets into weapons capable of destroying everything in their path. Much of this depends on what the bloodthirsty god of roguelike randomness decides to give you, but no run is doomed by bad luck alone. There is always a way to build a winning strategy from the tools available — you just need to figure out what it is.

The Economy Behind the Defense System

[c]Being eaten by aliens is not considered an acceptable reason for reduced productivity.[/c]

From an economic perspective, the system is relatively simple. There are recipes for turrets and defensive modules, and building them consumes resources. The more powerful the defensive system, the more numerous and rare those resources become.

This means you often have to choose between two approaches. You can search the shop for equipment that works with resources you already produce, or you can expand your production to unlock defensive systems that better fit your strategy.

Many parts of this system are still evolving, but the core idea remains the same: combat should be connected to the rest of the ship. The defenses you build, the resources you produce, and the layout you create should all influence each other.

That's all for today! We'd love to hear what you think about this kind of post. Are you interested in more deep dives into the game's mechanics and the design decisions behind them?

And of course, if you have questions about the combat system, or if Hull Rupture reminds you of another game (especially an obscure one), let us know in the comments!