Explosives and Shells Guide

If you want early Dark Fog fights to stop overwhelming you, or you need a better shell-based defense line later on, explosives are the path that turns simple fuel into real area damage. Start with the cheap option that helps your power grid and your weapons, then scale into heavier ammunition only when your logistics can actually support it. This guide walks you through what to unlock first, how to set up production without clogging your factory, and how to actually use Combustible Units, Explosive Units, and Shell Sets in combat.

Start with Combustible Units as your first useful explosive

Make Combustible Units your first serious explosive line. They are crafted from Coal in 3 seconds, and they do two jobs that matter right away: they are a very efficient early fuel for Icarus and Thermal Power Plants, and they are also a grenade-like weapon you can throw at clustered enemies. If you are still early in progression, this is the item that lets you solve power and combat with the same production line.

Use them as soon as you can if your goal is convenience. They are slightly more energy-dense per item than Energetic graphite, but Energetic graphite is still more resource-efficient from Coal. That means the right choice depends on what you need most: if you want better output per item and a stronger combat use case, lean into Combustible Units; if you are trying to stretch Coal as far as possible, Energetic graphite still wins on efficiency. In practice, either one can carry early power, so do not overthink it—standardize on the one that fits your logistics best.

Here is the quick reference you can use while planning your first explosive line:

The combat use is what makes Combustible Units stand out. Throw one and it explodes in a small area, dealing high explosive damage. That is enough to clean up clusters of Dark Fog units and chip down Planetary Bases from a distance. At close range, they become even better: Icarus can throw the next one as soon as the previous explosion resolves, so repeated throws produce very high damage output. If you spam them at minimum range, they will not damage Icarus itself. That makes them one of the safest and strongest early tools for breaking Dark Fog pressure.

Set up a simple Combustible Unit line before you add heavier weapons

Treat Combustible Units as a foundation item, not a niche recipe. They are simple to manufacture in large quantities, and that matters because they are useful in multiple places at once. Keep enough for fuel reserves, keep a small combat stock, and only then start spending the rest on downstream weapon recipes. Since they also appear in Missile Set and Shell Set, a healthy production line here pays off for the rest of your early and mid-game combat chain.

If you are using Proliferator, spray Combustible Units. The bonus is an almost free 12.5% extra energy, so it is one of the easiest fuel upgrades you can get. That makes them even better as an early power buffer, especially if your grid is still balancing between mining, smelting, and your first military builds. Just do not burn your whole stockpile in power plants if you expect a fight; keep a combat reserve so you can respond quickly when Dark Fog pressure spikes.

The best practical habit is simple: make one reliable Combustible Unit line, feed both your power and your emergency weapon supply from it, and let that stable base support your later ammunition chain. If you do that, you will not have to rebuild your fuel infrastructure when you decide to start defending seriously.

Build Explosive Units only when your mid-game logistics can support them

Do not rush Explosive Units as if they were a better fuel. They are not. They are an advanced intermediate for weapons, and that is where they earn their keep. The recipe pulls from Coal, Stone, Water, and Crude Oil, and it takes 6 seconds to craft. That mix makes the line much more demanding than Combustible Units, so you should only set it up once your basic resource flow is already stable.

The reason to build them is ammunition, not electricity. Explosive Units feed Supersonic Missile Set, Crystal Explosive Unit, and High-Explosive Shell Set, so they become important when your defense plan moves beyond simple early weapons. They are also tied to higher-tier production chains that involve High-purity silicon, Titanium ingot, and other high-tier components. In other words, this is not a recipe to slot in casually. Add it when your factory already knows how to move mid-game materials without stalling.

Keep Explosive Unit production near your chemical lines. Coal is shared with both Combustible Unit and Plastic, and Crude Oil is shared with Plastic and Sulfuric acid, so scattering these across the base only creates transport clutter. A clustered block is easier to manage: put the Explosive Unit line near your Plastic and Combustible Unit production, then pull Sulfuric acid in from a separate district. That arrangement keeps the recipe chain compact and makes it much easier to scale once your ammunition demand rises.

You can throw Explosive Units directly as a weapon, and they hit much harder than the lower-tier explosive. They are strong enough to destroy a mobile Dark Fog ground unit in a single hit even at high threat level without extra performance upgrades. Do not count on them for everything, though: their explosion radius does not reliably connect with Guardians, so they are not the answer for every target. As fuel, they are a poor choice; the energy per stack is high, but the production cost is even higher, so you should not burn them for power unless you have absolutely no better use.

Use Shell Sets as your first real area-damage ammunition

Once you want defenses that punish groups instead of single targets, move into Shell Set. This is ammunition for turrets, and you can also equip it on Icarus. A Shell Set contains 12 shells, and each shell uses efficient Combustible Units. When fired at a target position, it detonates immediately and deals Kinetic and Explosive damage in an area.

That immediate detonation is the key thing to exploit. Shell Set is best when enemies arrive in clusters or waves, not when you are trying to chase fast, isolated targets. Put it where groups of Raiders are forced to bunch up, and let the wide blast radius do the work. It has high damage and broad clearing power, which makes it much more useful for defense lines than for dueling one fast enemy at a time. Use it alongside other turrets rather than as your only answer.

You should also keep a small Shell Set stock for Icarus. Even if you are not relying on turret use, this ammo line gives Icarus its highest attack power among the available ammunition types. That alone makes it worth producing in modest amounts, because it gives you a strong emergency option when you need to help a defense line or finish off a dangerous cluster yourself.

A useful habit here is to produce just enough Shell Set to keep a turret line supplied and reserve a small stack for your own ammo slot. If your enemy problem is “many weak things at once,” Shell Set is the answer you should scale into.

Upgrade to High-Explosive Shell Sets once basic shells stop keeping up

When Shell Set defense starts to feel thin, step up to High-Explosive Shell Set. This is not a different combat role; it is a straightforward upgrade to shell production and power. The big thing to know is that its bottleneck is the Explosive Unit chain, so if that line is not stable yet, do not rush the upgrade.

This is where your earlier planning pays off. If you built Explosive Unit production in a clean, clustered block, you can feed High-Explosive Shell Set without turning your factory into a transport mess. The upgrade is especially worth it when you already rely on shell-based defenses and want stronger throughput or damage. Once you are at that stage, the improvement is practical rather than optional.

Also remember that proliferating ammo gives extra shots per box based on the extra products bonus of the proliferation level. Because Shell Set and High-Explosive Shell Set come in boxes of 12 shells, every crafting bonus translates directly into more shots you can field. If you are already proliferating ammunition elsewhere, carry that habit into your shell production too. It is one of the cleanest ways to turn your combat logistics into more actual firepower.

If you follow that order—Combustible Units first, Explosive Units only once your mid-game logistics are ready, then Shell Set and High-Explosive Shell Set as your defense line matures—you will get a smooth combat progression instead of a factory that chokes on its own ammunition supply.