Pathology Rework: Generation, Symptoms, and Transmission

[XyzzyThePretender]

[help wanted][input wanted][rework][WIP][balance]

About the PR

Unifies benign and malevolent symptoms into the symptoms file. Creates a dedicated transmission file for coding the new transmission system. Cleans up the main pathogen.dm by moving all transmission-related content. Cleans up pathogen generation to be simpler and more understandable.

Hopefully, this is the PR that marks the inflection point for pathology. Sentiment is not great, but I hope that this PR will finally work to resolve the most atrocious parts of playing with old pathology enabled.

I plan to make more PRs to fix pathology. Here is a living design doc that I am using to guide my work: https://hackmd.io/@XyzzyThePretender/B10Kp-DP5

Why's this needed?

The old transmission system is not good. Contagious diseases spread way too fast and mutated too quickly for anyone to properly respond. If pathology is to return, transmission must be completely reimagined. Isolation is no longer the only option. No single disease shall ravage Space Station 13 as was in the past. Pathogens may still be deadly, but the crew now stands a fighting chance to endure and recover from epidemics, natural or intentional.

Issues to address:

• Rebalance and standardize the code for every symptom
• Rework the rarity system into the expandable threat system
• Rework how transmission is controlled
• Setting a hard cap on cumulative infections per pathogen
• Coding a selection system for the chemical cure of a pathogen (also consider nonchemical cures like sleep, eating certain foods/drinks, temperature, exercise, etc.)
• Coding a new procedural generation system for pathogens with factors from the CDC-tiered system from PR#8710

Issues I need help with: (will update as I work, likely focus on how to handle proximity carrier-available checking)

Further features to add jointly with other PRs:

• Renaming a pathogen (help with word filters)
• Growing pathogen cultures in petri dishes

Follow-up PRs:

• Additional transmission types
• Additional symptoms
• Additional curing methods
• Playtesting Rebalances

This PR won't be ready to merge for some time.

Changelog

(u)XyzzyThePretender
(*)Pathogen transmission is much simpler and less disgusting.
(+)A disease can only cause a hard capped number of cumulative infections before losing contagion.
(+)No more shall there be puddles and fart clouds of sick somehow identifiable by the pathogen name.
(*)Pathogen generation is revamped.
(+)Natural spaceborne illness is possible (don't worry, it's not contagious!)
(+)Pathogens, once fully documented, can be named!
(*)The CDC has finally updated its manual on symptoms.
(*)Pathogen cures are simpler, immediately effective at preventing sudden explosive death, and more variable.
(+)Dealing with an epidemic is now possible within the bounds of regular gameplay. Difficulty may vary.

[github-actions]

Created discussion thread: https://forum.ss13.co/showthread.php?tid=18894

[XyzzyThePretender]

see below