[Feedback on proposal to extend Alien Embryo (xeno) gestation system]

What I am Proposing

The Alien Embryo is used in xeno development. As part of a small space ruin I have been working on, and after watching a lot of xeno rounds, I'd like to propose some minor extensions to alien embryo behavior. I have drafted changes to alien_embryo.dm that:

• introduce a incubation_scale value to be applied to the existing stage advancement process. The larger the incubation_scale, the longer it will take to advance
• dead hosts have a flat incubation_scale of 2, this would mean xeno's are penalized for letting hosts die before they give birth
• frozen unconscious hosts (below 0oC) will not advance (those in cryo_tubes)
• cold hosts (0oC - 32oC) will advance slower, based on how far below ideal temp their body temp is
• the bodyscanner now reports the size of the embryo (tiny, very small, small, large, very large)
• antibiotics ("spaceacillin") is mildly effective at slowing down progression in early stages
• neurotoxin is extremely effective at slowing down growth at all stages other than final
• high dose of neurotoxin will kill an alien embryo if given in the early to mid stages of gestation. the dosage increases for each gestation stage (10u to 50u).

Treatment Protocol Summary

Quote

1. Immediately administer 15-30u of spaceacillin to any casualty with obvious signs of xeno impregnation.
2. If scan indicates recent gestation and toxin medical treatment is available, administer 20-50u of neurotoxin and scan for confirmation of embryo death. Note that the neurotoxin will cause severe damage to the patient which will require significant management. When time permits, remove embryo corpse via surgery.
3. If infection time is unknown or surgery is not an immediate option, store patient in cyro tube in frozen state until surgery is available.
4. If cryo is not available or while patient is in transit/during surgery, IV administration of spaceacillin or neurotoxin to maintain blood levels is prefered. If using neurotoxin, recommend include toxin healing treatment in IV mix.

Why it is good for the game

Xeno rounds are fun, but there is little "agency" for those within the round. As an example, existing changes to spiders to introduce a toxin effect over time, gives medical staff actions to do - making the round more interesting. It is rare to see someone try to cut out an embryo, as there is no way to slow down the infection.

The proposed changes give a tangible chance for the medical staff, and others, to delay progression while they can conduct surgery. Conducting surgery in a xeno round, to remove an embryo, is really incredible. Additionally, once crew are aware of it being a xeno round this gives the opportunity for the medical staff to begin preparing. Neurotoxin is a narcotic, not normally allowed. In the same way engineers in an emergency are authorized to tear the station to pieces for necessary goals, this could involve the CMO authorizing the production of neurotoxin (and spaceacillin). The neurotoxin is also somewhat like chemo is in real life - it will require treating in its own right as it will kill the host as well. The use of spaceacillin fits with its description and existing use case (slowing the progression of disease), as well as existing use to slow parasites.

My proposed approach

So far I have all of the above working. My plan is to check for broad agreement first, and then submit these changes for review if there is broad interest in it. 

The following caveats exist:

• The current lethal doses of neurotoxin for the embryo just outright delete the embryo. I plan to change this so that they will damage the embryo over time, until the embryo "organ" is dead. Then leave the dead embryo inside. This requires some testing, but would bring the organ in line with other organs.
• I have not wanted to touch many files. Currently the way the bodyscanner works, is that the "desc" for the embryo only shows in the printed version, not the screen version. I don't plan on changing this as I want the PR to be as simple as possible. Little steps!
• These changes are wrapped up with the addition of an AI only variant of larva and facehugger, as I want to use these for a proposed space ruin. However, I will likely comment these out for the PR to keep things simple.

If the PR is submitted and then approved I will update the Wiki and prepare a in-universe book detailing proposed treatment protocol from an in-universe document perspective