So my question is what would make an army of droids unstoppable when facing against humanoid species? (specifically how would droids be designed)

For context one person sets foot on a planet with very advanced technology, but its inhabitants lack imagination to use it to Its full extent. The outsider starts modernizing but this upsets the natives. And so a war begins. Other planets come into play in the conflict (due to them being political allies) and so one person with factories at his disposal has to create an army capable of defeating the threat. By defeating I mean either negotiate, incapacitate or destroy the attackers. Having to conquer planets for resources is a likely turn of events.

The army needs to be entirely mechanical (no biological components, unless we are talking about a biological weapon like diseases). The machines or droids need to be capable of defeating armies ranging from battleships to foot soldiers. There is no concern about cost, as there are fully autonomous factories at their disposal. The technology is advanced enough to have quantum computing, space travel (distortion), artificial gravity, plasma weapons and forcefields. Materials that can be used are everything found on the periodic table, no fictional elements!

This mechanical army is facing fleets of battleships and armies on the surface of the planets. For reference look at everything from Star Trek, Star Wars, Starship Troopers ect… The battle is mostly defensive in nature as the purpose is self defense, to protect one individual. However you may want to take into consideration the fact that some races don’t surrender or negotiate and need to be eradicated for the threat to disappear. So yes, conquering planets and killing off the population is allowed.

So far these are the things I’ve got figured out:

The battleships would obviously not be designed for organics. The ship is basically a giant droid with an autopilot. They are no corridors, instead droids are stored in the ship, ready for deployment. Instead of hallways a series of tubes transport things across the ship. Each ship is equipped with a factory and refineries in order to construct additional troops, bases and more ships.

Infantry droids are mass produced and are lacking in power. They make up with their numbers and compactness making them easy to store and produce. They have a basic AI that allows them to function independently, however they require a central command to direct their movements. Droid generals need to present to coordinate the movements of the troops especially since they will often be outside the transmission range of a battleship. So far my best artillery droid is like a mobile turret that can roll itself to a new location, lock into place and fire at will. They can also fire while rolling.

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    $\begingroup$ More context needed. What level technology are we talking about here? Also, what is the goal here? Subjugate the natives? Exterminate them? $\endgroup$ – Priska Oct 20 '19 at 12:17
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    $\begingroup$ Absent any idea of what or who might be trying to stop your droids, its hard to answer this question well, and it isn't clear what would make one answer better than another or even "Right". Have a read of the relevant bits of the help centre. $\endgroup$ – Starfish Prime Oct 20 '19 at 12:51
  • $\begingroup$ No additional context needed. How does one quantify level of science-fiction technology? Goal: defeat. Destroy or incapacitate. $\endgroup$ – user69494 Oct 20 '19 at 12:51
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    $\begingroup$ @LiveInAmbeR quantifying the technology in your world shouldn't be difficult. Broad strokes are enough, or even suggesting similar fictional settings. The presence or absense of science-fantasy technologies like FTL or teleportation or grey-goo is quite important here. I'm not trying to be mean; I like this sort of question. But please do focus it down, or you risk it being closed. $\endgroup$ – Starfish Prime Oct 20 '19 at 14:35
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    $\begingroup$ I think based on what you said that you want some of the following constraints in your question: humanoid droids, microscopic self-replication only for diseases. Most depopulation happens by the boots-on-the-ground armies rather than orbital bombardment, nukes etc. Technology is basically WWII with lasers, space battles are the naval-in-space trope with fighters, carriers and battleships. The question: what kind of droid army would have the least drawbacks to win a war against biological equivalents. Pick the best answer as winner but have no fear USING the coolest answer for your story. $\endgroup$ – Demigan Oct 20 '19 at 15:43


Having a billions of microscopic droids, especially ones that can "replicate" (make other nanodroids) would be almost impossible to stop.

  • Can crawl into people's bodies and lay dormant without detection before killing them (by stopping their heart, shredding their brain, etc)
  • Can crawl/fly into the most difficult facilities using air vents, exhaust pipes, sewer drains
  • Can infiltrate any other computerized equipment and destroy motherboards, capacitors, or other difficult-to-diagnose problems which would require full replacement.
  • Can self-detonate in oil drums or near explosives. This couple with the ability to hide means they could embed themselves on bombs, torpedoes, etc, and then detonate the explosive before it's fired - either right away or waiting for the optimal time.
  • Can spy on and report back what is happening in secret meetings; can simultaneously track the movements of any and all enemy forces.
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  • $\begingroup$ This answer makes me think it's an answer to the Fermi Paradox. All you need is some military to read it and now we're all doomed... $\endgroup$ – flox Oct 20 '19 at 13:17
  • $\begingroup$ @flox who says I didn't get the idea from the military? $\endgroup$ – cegfault Oct 20 '19 at 15:24
  • $\begingroup$ just kidding, but yeah, I guess this is a little too plausibly scary $\endgroup$ – cegfault Oct 20 '19 at 15:24

Update your question to be easier to answer (or answer at all), but I'm not opposed to adding an idea.

If we stick with humanoid robotics, which considering your question is likely, and that these robots are as capable as dogs/humans depending on their purpose rather than AI that would easily outstrip any human knowledge and come up with better idea's which also seems to be a point in your question. Then I would create several series of bots.

The first are cheap and easy to produce with low intelligence. They'll do basic stuff like take cover and recognize friend from foe, but will not have a lot of tactical insight in what will happen in the future. These are designed to be easily mass-produced and force the enemy into cover. The enemy cares about their lives, these droids dont care too much. The robots care a little so they dont just stand in the open and get mowed down. These droids have space in their minds to upload a few tasks besides their basic programming, allowing them to become a workforce that can do more complex maintenance, construction, creation of works like canals and trenches etc. This also means that a demolitions expert can be created on the spot when the right info is directly placed into them. Naturally you need a direct connection like an USB rather than wifi or something otherwise its a bit too easy to hack them.

Supplementing these are droids that look like the cheap one's but are much more capable. These hide in plain sight with their brethren but have better accuracy and survival instincts. These could also function as squadleaders and order their lesser brethren around to the benefit of these superior robots.

Then there are command and control droids. These would most likely be vehicular in nature to transmit and receive all information required. These robots have a selection of command droids at their side with all the tasks the cheap fodder can do inside, allowing one command droid to go up to any cheap droids and upload the necessary programs. For security reasons the most basic functions of the droid are seperately stored inside in case an enemy tries to use fake command droids to safely reprogram enemy droids.

Then there are specialist droids. Basically the special-operation groups but build to match their respective tasks. Need your droids do a frontal assault? Get a few tough droids with lots of frontal protection to lead the charge. In tight corridors you have another type of droid etc. These can help the cheap droids in fights where their numbers arent useful enough to win the fights. As an extention to these droids most vehicles will fall in this category fulfilling all transport, AFV, tank and aircraft duties that need to be performed.

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  • $\begingroup$ You have no idea how happy I am to finally get a nice answer. I'm editing my question to have the necessary context, but I really appreciate your answer! $\endgroup$ – user69494 Oct 20 '19 at 13:45

Swarm Intelligence hive mind

This droid will make the most of AI, big data and Communication technology.

This work like this:

  • each droid contribute a little of its "thinking" (CPU) power. => there are no "commander" to take out, no weakpoint.

  • each droid contribute a little of its collected data (what it see ...). You can think this is how droid share "knowledge". Small, forward droid mark the target for long range droid.

  • each droid uphold the effiency of the group, may not concern their own safety if there are better outcome for "group" => Ex: small droid take cannon shot that will likely to serious damage big droid (to pull it out, droid need 2 above condition)

When in the "big Swarm" (together with battleship), droid have better Intelligent, then will decide grand strategy, deploy troop, ...

Then, in the small group, outside communication range of the "big swarm", droid should have lower intelligent, and will carry out predefine objective (kill X, bomb Y, ...). But in tactical level (take cover, firing solution, hand-to-hand combat,...) droid can think themself.

The Geth is Mass Effect 3 is a good example.

But what really make droid unstoppable: Attrition warfare

Droid can mine for more resource, raw resource like metal, and knowledge, data.

Droid use raw resource (metal, ...) better effiency, can recycle dead droid (but dead human is dead and must be reborn, raise, train again).

Knowledge, data collected combine with hive mind make droid adapt faster than human, furture increase resource usage effiency.

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  • $\begingroup$ I agree with the efficiency of the system, however they rely solely on communication for their shared computing power, which means disrupting it will take away their intelligence. Having a commander droid means the troops have a weak point, yes. But the intelligence does not go away because the network crashed. Another thing is that "each droid upholds the efficiency of the group" means that each droid destroyed lowers the intelligence of the group. $\endgroup$ – user69494 Oct 20 '19 at 14:30
  • $\begingroup$ the network cannot crashed because peer-to-peer connection. There are no must-have central node. Instead of having central command (1 big droid CPU), why not have central command (one big CPU) + many small droid (many small CPU) ? $\endgroup$ – Haha TTpro Oct 20 '19 at 14:40
  • $\begingroup$ The Geth seemed always so vulnerable to me. Just filling the air with radio noise can work, this is why ground-based drones in reality have a hard time working while flying drones can ignore any signal from below as they use sattelite. Damaged drones would also start feeding erroneous information to the swarm. Not to mention that the friend-protocol can be hijacked as they need to be able to link with new units/their old units when they come into range. Even harvesting droids from the battlefield and using their processors and equipment to send false data would be an option... $\endgroup$ – Demigan Oct 20 '19 at 15:30

So I’m always of the opinion that we can draw inspiration from the real world and then extrapolate it to wherever we want.

Currently, all successful military forces use combined arms tactics and have for a very long time. What I mean by this is that they never put all their eggs in one basket. For example, let’s say that one military power has developed tanks that are absolutely unstoppable on the ground. If they don’t have some level of support from the air or anti-air defenses, these unstoppable tanks will become smoking ruins very shortly. Meanwhile, if a military force has untouchable fighter-bombers, if they don’t have capable ground forces or a capable navy, they won’t be able to utilize those planes effectively. “But how does this relate to my question?” Well I’m glad you asked!

See, if you want an unstoppable droid army, the most basic thing to remember is that you will need many different types of droids. To borrow from the other answers, nano-swarm droids, command and control droids, infantry, special forces, workers, engineers, and battleships will all be necessary. In addition, you will need fighters and bombers (if not in space at least in the atmosphere), gunships (think helicopters) to support ground troops and take out heavily armored targets, and possibly naval units, because if the target planet has water it will have a navy. Finally, and definitely don’t overlook this, your army will need cyber-warfare units, both for offense and defense.

As a last few notes, remember that modern robotics is often limited by the power and size requirements of our batteries, so depending on how advanced you want these droids to be, they might have problems with keeping smaller droids powered. Also, droids have the wonderful upside of being modular if you want, meaning that each and every droid can be armed, armored, and equipped for specific missions and completely change their load out within minutes. Lastly, while your droids certainly can develop biological or nuclear weapons, (or worse depending on how exotic you want to get), I would avoid using these on planets, (especially the biologics or chemical weapons), as that will drastically reduce the chance of any biological species negotiating a truce with you. They’re kind of funny about the whole being wiped out by plague thing.

So, to summarize, multiple drones to fill different roles, manage power requirements, make modular designs, and be careful with your PR. After a few systems fall to your war machine, the others will suddenly be considering a truce to be much more viable.

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  • $\begingroup$ Did you read the question? I had planned to diversify the droid army and was asking for your help. Also about the negotiations they either do or don't. If they don't there's no choice but to wipe them out. Or are you simply talking about the fear factor? $\endgroup$ – user69494 Oct 20 '19 at 15:31
  • $\begingroup$ Weapons like biological and chemical weapons tend to push the people who do want to negotiate into the don’t category, so while those weapons will certainly make the droids fearsome, it will push potential allies away, provide excellent PR ammunition for your enemies, and make everyone fight that much harder to take them out. Remember, an enemy who feels like he’s backed into a corner will fight much harder than one who feels like he has a way out. $\endgroup$ – Nick Oct 20 '19 at 20:05