After finding a dead Deathwatch Space Marine aboard a derelict Inquisitor Space Hulk that was wiped from all records by the Inquisition due to Heresy and Chaos involvement and doing little more than sticking him in the freezer so he doesn't start rotting while we figure out what to do with him... I have started formulating some plans...

As an Explorator, my job is to investigate things. One such thing I would like to investigate is just how easy it would be to re-create a Space Marine from a Gene-seed. I have an intact Gene-seed, and a willing host, (well, he has said that he would like to become a Space Marine... that doesn't necessarily mean he'd be willing for me to shove a Gene-seed in him while he's sleeping).

So, in game terms, how easy would it be for me to create a Space Marine from a Gene-seed?


4 Answers 4


Space marines carry out constant trials to find the best of the best on dozens of worlds, those that pass the first test are taken to the home worlds and further tested to make sure no one got through with just a passing grade.

Form there it takes one year to produce a space marine using lost technology, all of which the candidate spends unconscious as multiple new organs are installed and there muscles artificially augmented. This process has around a 20% failure rate.

Your willing host would probably die about 30 seconds into the process.

The gene seed is a control organ, it regulates the rest of the implants and allows the space marine to integrate into his armor wearing it as a second skin.

You are missing the second heart, the third lung, anti toxin glands, toxin sacks for the jaw (yes a space marine can spit acid like alien), brain hemisphere separation and a dozen others. If you are interested the Deathwatch core rule book goes into great detail on how a space marine is made, what is added and what it does.

I doubt you could successfully harvest all of this from the dead marine or the gene seed for the matter. It is incredibly hard to harvest a gene seed, even space marines need specialized equipment for a 50/50 chance of success.

Also consider a gene seed is to a space marine chapter what a piece of the true cross is to a devout Christian, and you have a Deathwatch gene seed. I would not be surprised if the planet you were on simply explodes if word gets out; the inquisition is funny about their secrets.

  • \$\begingroup\$ I suspect there may be a significant reward for returning a fallen Space Marine to his fellows. After all, they have things they can do with that gene seed. \$\endgroup\$
    – T.J.L.
    Commented Jun 10, 2016 at 12:25

DIY Astartes, or So You Want To Play Emperor

First off, I need to stress that this is a VERY BAD IDEA. The Space Marines were made by the Emperor Himself, and making your own would be akin to playing Emperor, which is so much heresy the Inquision would leap onto your ass until your butt resembled an auto-da-fé. Plus, the existing Chapters will NOT like you for this. Everyone from the big names like Logan Grimnar, Dante and Calgar to little guys like the Mentors or the Genesis Chapter (and no, they are not lead by Space Phil Collins... as far as we know) would line up to cave your face in. But still, you want to build yourself a Space Marine within the context of Rogue Trader? It could be done, but you'd run into a few problems.

The problems with gene-seed

Not all gene-seed is, so to say, "perfect". Some of them display various defects that alter the Space Marines they are implanted into. For example, the Blood Angels and their successors have the Red Thirst, which makes them go crazy. Trying to engineer this out is nigh impossible, as the Blood Angels will attest. The Raven Guard lack the Mucranoid (super-sweat that protects them from extreme temperatures) and Betcher's Gland (acid spit), the Imperial Fists lack Betcher's Gland and the Sus-an Membrane (allowing the user to enter a state of suspended animation that the user has to be woken out of by someone else), the Space Wolves have the Canis Helix and the Salamanders have a malfunctioning Melanchromic Organ, which prevents them from lightening their skin when not exposed to extreme radiation. It is not known what happens if you do implant these things in a Space Marine, but it's not a smart idea to try and find out because it can result in either the death of the applicant or maybe even of the gene-seed itself. So you'd have to figure out what the defects are (you still have the body, take a look at that!) and obtain parts for the next step.

Avengers, assemble!

Then you need to get your hands on the parts. Some of these like the Second Heart or the Multi-lung should not be too difficult to obtain, but the rest is a lot more interesting. You can't just go knock on the door of some Magos Biologis and ask him if he's got an Omophagea he doesn't need, you attract attention that way. Do get your hands on these parts you'd have to either harvest them from the Adeptus Popsilicus you have in your freezer (difficult if the tissue is dead), find a renegade Biologis (bad idea), go visit the Dread Biologis of Forge Polix to get some parts (worse idea), steal them from either renegade Space Marines (VERY bad idea) or from a Loyalist (EXTREMELY BAD IDEA), or barter with the likes of Fabius Bile to get some parts (OH SWEET EMPEROR WHY). A possible solution would be to harvest the parts from the corpse and see if you can grease the palms of a renegade Biologis to get the parts back up and running.

Do you want to build a superman?

Even IF you get your hands on all the parts then comes the problem of, erm, assembling your pet Space Marine. You could try and combine it with the above if you made a deal that you should not have and use their Marine-building facilities, or you need to find them yourself. But where do you find those?

It is possible, but I'm not certain of this, that once a Renegade Chapter leaves its home world their facilities will be left untouched. You could try and raid abandoned Space Marine homeworlds to get your hands on some bits of the machines used to put a Space Marine together, and go from there. You can either try this on a Renegade world (though it's possible that these machines were either destroyed or taken along) or on a world whose Marines were all eaten by the Tyranids (but it's possible that they have been eaten as well). Or you can see if you can pay off a group of Renegades to allow you to assemble your Space Marine there (but they'll turn on you because you have everything you need to build yourself a Space Marine, a resource they will want for themselves).

Also note that building a Space Marine takes a while: anywhere from 2 to 6 years. And even if you find yourself a fit host, there's a likely chance that they die from the procedure, so be sure to order extra hearts by the dozen. And do find someone who knows how to assemble a Space Marine: either the renegade Biologis or get someone to minmax their medical skill.

So you got a Space Marine, now what?

Training and indoctrination. A Space Marine is only as good as their training, so you need to design yourself a way to train your Astartes. Both during the treatments and after, so they can fight effectively. And indoctrination is important as well; Space Marines are faster than any human, control their senses and nervous systems, endure pain that would kill a man and have photographic memories. And do make sure to teach him not to rip your head off when you're done, because that would be a shame. Hilarious, but a shame.

Also, equipment. You could try and fit the old armor onto your guy, but do remember to find ways to maintain it (not very common and certainly not public knowledge) and arm it (you can't exactly buy Bolter shells fit for a Space Marine in any port, you know).

Primed and proper and ready to purge

And now you have a Space Marine, congratulations! Do make sure to keep him out of sight of any regular Space Marines, because they'd see him as an abomination. And when you have Loyalist forces on your bridge for a bit, do remember to put him in the cupboard under the stairs or something (plenty of space there: going by the standards of a Rogue Trader those cupboards should be the size of villas).

Also, note that there are no rules for most of this: it's all ideas for you to do and your GM to make rules to. Do expect them to baulk at this though: making your own Space Marine is a Violation of the Holy Human Form, one of the worst heresies imaginable.

  • \$\begingroup\$ Upvote because it's an amazing answer, besides the fact it made me cry from laughter \$\endgroup\$
    – Nyakouai
    Commented Jun 10, 2016 at 13:13

Just how SevenSidedDie pointed, it takes more than just a gene-seed to create a Space Marine. You need a wide array of organs and implants, and a team of experienced apothecaries, and the process can last for years. Not only that, the reciever of the organs and the gene-seed must be 18 years old at most, and has to be strong enough to survive the drastic modifications in his body. Not all the recruits survive the process, even though only the strongest and most able are selected. Also note that if the gene-seed came from a Space Marine who was involved in Heresy and Chaos, it's most likely to be corrupted or severly mutated. So, no, it's pretty much impossible for an explorator to create a Space Marine, much less just from a single gene-seed.

What you can do is to preserve the entire Astartes body, with his armor and weapons (if there were any) to later retrieve it to his original chapter. The chapter would regard this as an act of honour, and your party would have a slightly better relationship with this particular chapter. (note, however, that the chapter's reaction can vary a lot depending on which one it is)

  • \$\begingroup\$ By "at much" do you mean "at most"? \$\endgroup\$ Commented Feb 6, 2015 at 4:12
  • \$\begingroup\$ Totally! I will correct it now! (English is not my first language, sorry) \$\endgroup\$ Commented Feb 6, 2015 at 16:10


You have the tools or usable equivalents, and you should have the knowhow, but the risk of failure is high, and the result will not be a true Space Marine. In plot terms, this means that if the GM says yes, you have an almost Space Marine on your hands, as it wouldn't be particularly interesting if it failed.

What you have

A lot of the answers claim that you don't have access to the various organs that make a Space Marine. They are mistaken. All the Space Marine implanted organs have one source, the gene-seed. You can't just shove the seed into the guy, that would certainly alter him, he'd get stronger, tougher, faster, but he wouldn't even be close to a Space Marine.

What you do have is cloning vats. Space Marine organs are all cultivated from the gene-seed, that's all you need to get started, the forces of the Lost and the Damned have been making Traitor Marines with less for ten thousand years, compared to what they're doing, you've got it easy. Your ship almost certainly has the vats you need on board, and if not, you can buy them with no questions asked.

What you don't have

You have all the organs thanks to the seed, but you're missing some of the inorganic implants. The Black Carapace is a big one, however, it isn't necessary. You can do without it, try taking the one from the dead Marine you have on board, or build an equivalent yourself. I'd recommend the former or the latter, there's no need to increase the risk of failure just for the Carapace. Without it, the only effect will be that unlike a true Marine, yours will not avoid the penalties of wearing Power Armour, he'll act the same as any other power armour user.

The other inorganic ones are either not necessary, or not unique to Marines, meaning you can get a hold of or make them yourself.

The procedure

First of all, there is a major issue you need to address. Your volunteer. Once your volunteer hits a certain age (I personally go with 25 for several reasons) they will no longer be a viable candidate. You can try it anyway, there are ways to make it work, such a rejuvinens or less expensive hormonal treatments, but that's adding more risk of failure to an already very risky procedure. Your ideal candidate will be around 9 years old, though as old as the early 20's should work.

The sex of the volunteer should be male, again, you can try and change this, but the risk of failure would approach 100%. That said, if this is happening, the rule of plot dictates that it will succeed, so go nuts.

Once all the organs are cultivated, you can go about the implantation process. There are better sources to find out the order and function of each organ, so I won't go into details. The full process should take years, but there are cases of far shorter augmentations, so much like most of the above, you can treat that as a guideline not a rule. A lot of that time is physical conditioning and brainwashing, both of which can be skipped.


So many things can go wrong with this that I wouldn't even attempt it unless the GM is on board and rule of cooling it, or if you have a brilliant chirurgeon aboard. To do this with rolls rather than GM fiat, you need somebody who basically can't fail medicae rolls. Totally possible to get a medic that good as a player character, but good luck finding an NPC like that if you don't already have one.

Even if it's successful, there will be problems. As I said above, your Marine won't be able to wear Power Armour as if it were a second skin, like he would if he had the Black Carapace. On top of that, the defects of the gene-seed will have an effect. You'll need to do a full autopsy on the dead Marine to check whether their chapter has any variations on the augmentation procedure. Some organs may be left out, or augmented with cybernetics, and you can't f#$k that up.

Any defects the chapter has will be present in your Marine. Almost no Space Marines have functioning remembrancers, and most don't have working Betcher's Gland's either. Any mental defects from the chapter will cause issue, the effects could be more pronounced or less pronounced due to the lack of extended brainwashing.

All but the most slapstick of complications will only be apparent after the surgery. The volunteer may die, horribly. You may be able to try again if it fails, but that's pretty sketchy. This procedure is practically mundane compared to trying it again if it fails.

Final notes

Despite what it might seem, this isn't actually all that unusual. All new Traitor Marines are created in far less ideal circumstances, and provided you have a good chirurgeon, you quite literally have everything on hand that the actual Marines have, save for the Black Carapace. The odds of failure are so high due to the odds of failure for the legitimate procedure being so high, and in 40k, rule of cool means that those odds are basically irrelevant. Corruption for everybody involved is likely, but if that happens, the odds of success go up dramatically as well.

The risk of discovery by the imperium is far higher than the risk of the procedure completely failing. So I say go for it.


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