Mecha and Roleplaying Games both love action scenes. Rare is the piece of fiction belonging to either that doesn't involve the bad guy (or girl, or monster, or giant robot) getting beat up for the big climax of the story... Or any time they need to make an antagonist feel threatening at all.
That said, sometimes it is more about threatening the character's mental stability instead of physically hurting them. Characters get more and more messed up in the head with the passage of time, even those that are invincible on the battlefield.
GGG had a system for handling that in the past. It was exactly the same as the system for physical combat, for simplicity's sake, and wasn't all that good as a consequence. I think it is about time that gets fixed, but there's a few things that need to be kept in mind:
Turning elements of mental trauma into a game is never realistic, because what makes things fun in fiction often makes them very different from how they are in real life. This gets more complicated in a game about flashy action scenes, larger than life characters, and kicking reason to the curb in the name of coolness.The existing rules do handle things like being paralyzed with fear, running away from something horrifying, or similar consequences. It works off the usual Plot Armor rules and is meant to be a different way to knock someone out or defeat them momentarily.
However, Insanity is at its best when it is not just part of your Hit Points, because the fun part of roleplaying games with elements of insanity added in are its lasting consequences and long term damage. Another complication is that it is also one of those aspects of roleplaying where less is more, the more rules you attach to different types of mental illnesses, the more that you risk detracting from roleplaying them in favor of arbitrarily punishing a character. We have to work on the assumption that roleplaying a character's breakdown is fun (Otherwise why would you play a game where that is supposed to happen?) and enable that.
All of this is a gross oversimplification, and each of the previous paragraphs could stand to be expanded upon (or explained better, really) but it does serve as an introduction to the meat of this post.
Mental Damage and Plot Armor
Trauma takes its toll on the human soul, tragic things happen, and you are forced to readjust your beliefs and way of life in the face of things greater than yourself. The human mind and body are indeed fragile, specially when there are things out there that cannot
be understood with human logic and want to destroy everything you care about. PCs are heroes, they can face the worst the world has to offer and hold themselves together as long as they are victorious. But when they falter and their shells crack, something does get to them, leaving a permanent scar.
Any time a character is defeated as a consequence of Plot Armor Damage, they accrue one Insanity Rank per Layer lost this way. This is most common as a consequence of physical violence, but it will also happen if you just see something horrific happen to someone else, as well as when something clearly supernatural takes place. Indeed, a game of GGG intending to make use of these rules should make Willpower Tests to not take Plot Armor Damage from being witness to traumatizing things more common.
Insanity Ranks go from 1 to 10, measuring just how well you are holding up from what you've been through... Or rather, how you aren't. An Insanity Rank of 1 leaves you just a tad more unhinged than you used to be, but at Rank 10 you have more issues than Time Magazine. Along the way, you pick up Trauma Traits at Insanity Ranks 3, 5, 7 and 10. After Rank 10 the character has seen way too much and been powerless too many times. At the Players' choice the character can either become an NPC because they're too far gone, or can be institutionalized until they've had enough Therapy to go back to 10 Insanity or under.
You can pick your Trauma Traits from an example list, or come up with your own variants as long as it is clearly explained how they would come into play. A Trauma Trait is not purchased with PP, you just get them as a consequence of having Insanity Ranks. They are like a combination of Features and Genre Banes in that they each have a positive and negative side to them. The positive side is that they will give you more Genre Points, while the negative side is that you don't control just how and when they make you go crazy, the GM does.
Once per Episode per Trauma Trait you possess, the GM may force the Trauma's effects on you, and you can choose to either submit or fight it out. If you submit your character must roleplay the Trauma Trait as appropriate, but you gain a Genre Point out of it. If you fight then you must make a Contested Test of Willpower against the GM Testing your Insanity, should you win then you compose and maintain control of yourself for the time being... But should the GM win, you lose control of yourself to the Trauma Trait and play it out without gaining any Genre Points for it.
Therapy can mitigate this ticking clock of doom. Therapy Tests are made through the Diplomacy Skill, and remove one Insanity Rank from the patient for each multiple of 5 met by the result. A Character may benefit from only one Therapy Test per Episode Arc, however, and going below the Insanity Ranks required to earn Trauma Traits will remove them. Trauma Traits lost this way may come back the moment the character earns enough Insanity Ranks again, or may instead be replaced with new ones.
A Character may start higher up in the Insanity Rank scale than 0 if they want to, giving them the appropriate number of Trauma Traits.
Insanity Rank Descriptions
Rank 0-2: You can be a little on edge or obsessive at times, and perhaps the coffee of your life needs a spoon or two more of sugar, but you're fairly normal.
Rank 3-4: You're not crazy. You're just anxious and get nervous in situations most people don't, and sometimes you wonder if things make too little or too much sense. But you're not crazy and will repeat it as long as you need to.
Rank 5-6: You can mask it if you try hard enough, but anyone who knows you personally should be able to tell that you've got issues. Maybe you know you're crazy, maybe you don't, but it is getting hard to hell.
Rank 7-9: Legitimately unaware of what is and isn't real anymore, you're an inch away from hurting yourself and others.
Rank 10+: Tethering on the edge of reason if not completely gone already, you're likely living a nightmare in waking life. Suicide looks pretty good.
Traumatic Experience Difficulty Numbers
DN 5 - Facing an alien monster for the first time, Watching someone else being tortured in front of your eyes, Spending days in jail.
DN 10 - Watching someone die victim to violent psychic powers, Seeing years of hard work being lost in minutes, Spending days in solitary confinement.
DN 15 - Watching a monster take on human form, Losing your family in a tragic accident, Being deeply betrayed or lied to by a loved one.
DN 20 - Being tortured for days, Having a loved one die in your arms after you failed to save them, Killing another human being and eating their corpse to survive.
Example Trauma Traits
Terror - You are always under distress and feeling vulnerable, at times you experience sudden panic attacks no matter how calm the circumstances may logically be. Episodes can last from minutes to hours, with their consequences ranging from being paralyzed to a deeply uncomfortable nausea.
Flashbacks - When exposed to something that reminds you of a traumatic event, memories force their way to the forefront and you are in danger of reliving it. When this happens everything feels exactly like it did back then, physically and emotionally.
Depression - You feel tired and sour, you likely also have problems eating or sleeping to make it worse. This can get bad enough to hold you back from doing things that are really important, either because you don't feel like you can do it or you feel it is not worth it.
Blackouts - The character is prone to entering a fugue state and losing control of themselves for days at a time, ignoring everyone else and just idly hanging about until they wake up. They will snap back to reality if threatened or directly engaged, but this can make it impossible to get things done during downtime.
Megalomania - You are full of yourself these days, often acting with recklessness and arrogance with little to no provocation. As if that weren't enough, your hyperactivity and lack of concentration make you go seek out ways to get in trouble.
Hallucinations - You see things that aren't real, but even when you can tell the difference, imaginary fire still burns and the screams of imaginary people still keep you awake. At some point they will get you, and you will do something really bad while believing them to be real.
Antisocial - You have gotten violent, either out of hate or anger at everything and everyone. You could even be alternating between the calculated violation of the rights of others and flipping out in rage the next if it is bad enough.
Dependence - You cling to something or someone else to get through bad times, deferring to them whenever possible. Maybe you just ask another PC for what to do about every little thing, or perhaps you flip coins obsessively when it comes to yes/no questions, but you certainly don't trust your own judgement.
Delusions - You have your own explanation to make more sense of this nonsensical world. These range from flat denial of whatever happened to outright blaming everything on the inhabitants of fairyland.
Addiction - You're holding together thanks to taking in various chemicals in unhealthy doses and at irregular intervals. Alcohol, drugs and medication all change your mood in different ways, but the real problem comes from your desperation when you start to feel the withdrawal.
The above is just a way to use the typical elements of insanity that could make for a suitable adaptation to an action-centric game. More complicated and detailed depictions of mental illnesses, like a character suddenly beginning to suffer from amnesia or multiple personality disorder would complicate things too much to represent in a satisfying way. Not to mention it would be something of a buzzkiller as far as character development goes.
Mechanically, Trauma Traits are a slightly more hands-on approach to Genre Themes, retaining an element of rewarding Players for roleplaying in ways that are interesting if not exactly beneficial to the Characters themselves. Because they are meant to represent something that is outside of the control of the PCs, the GM is the one who brings them out to center stage. Their influence can be resisted, sure, but the threat of your PC losing themselves to their disorders remains, and that makes getting a reward for roleplaying them more enticing.
This is one of many ways in which Genre Themes can be rewritten into more interesting mechanics depending on the setting. They're the most malleable rule in the game, so this is not the last modification you'll see. Next time will be about Mecha Upgrades that once were part of the game but no longer do or were pretty close but didn't make it for whichever reason.