In 3:16 Carnage Amongst The Stars, I just drove the whole group crazy. Hallucinations, multiple realities, glaring inconsistencies, characters and situations that obviously couldn't exist, etc. It was almost all improvised, and I made no efforts to correct "mistakes" or obvious contradictions. Each week I just dove down whichever rabbit hole struck my fancy. This works really well when you're okay with the game not being taken 100% seriously, and when you're not really focused on long-term viability of the campaign. Honestly, I never expected that campaign to run as long as it did.
My Gumshoe Continuum campaign, on the other hand, is one I take very seriously, and hope to be running for a couple more years at least. We're about a year and a half into the campaign at this point, and just last Wednesday, I finally revealed that one of the PCs was crazy. He'd technically been nuts for about six months, but we played it real subtle. There was a scene where he nearly got Fragged Out (think of Back to the Future when Marty's hand starts to fade away: Frag's kinda like that, but it'll drive you crazy, too) , took a lot of mental Stability damage and snapped. So, the other players and I (as GM) decided on his specific brand of insanity, and warped the campaign around it. (That is, after all, the way the Gumshoe insanity rules work.) There was a minor NPC, who (coincidentally) had only ever interacted with his PC. So we decided she didn't exist.
Her name was Beverly, and she would eventually be nicknamed Beverly the Wallflower. When she was first introduced, I had every intention of her being a real character. The PC, whose name is Declan McGee, met her at a speakeasy in 1928 New York. She was just a bit of local color, introduced to establish a scene and was but one of like 50 details added just to make 1928 feel really different than modern day. 1928 was the PCs first major trip back in time more than a decade, and so I put some effort into making it interesting and "real". I had Declan run across Beverly the Wallflower a couple times, and was considering introducing a subplot where she starts stalking him, but hadn't really put much work into it yet. Like I said, none of the other PCs had met her yet (though one had most likely seen her across a crowded room).
Shortly thereafter, Declan failed the big Stability test after being Fragged (zapped by paradox), and the rest of the group got to conspire behind his back about what manner of madness had afflicted him. My wife suggested the awesome notion that perhaps her character hadn't actually seen Beverly across the crowded room, because maybe Beverly didn't exist. It was brilliant, and especially devious because it's not something anyone would see coming. If I introduce a character in September and in December your PC fails a stability test, you don't expect the consequence to be that the scene back in September didn't happen. But indeed, that's what we ret-conned behind the delusional character's players back. Effectively, we decided that he'd dreamed up an imaginary friend. He met his imaginary friend this one night in 1928 at a bar where he was feeling a little left out. From there it followed that every time the PC felt left out, lonely, or imperiled, Beverly would show up out of no where to make him feel safe and loved, even if he wasn't.
What can I say? I'm a bit of bastard (and while I'm at it, I'll add that the Gumshoe insanity rules rock). After a few sessions, good ol' Declan McGee was alone for a bit chasing a personal project while far away from 1920's NYC, and Beverly showed up to keep him company. Of course this was a shock to him, as nothing in those first few scenes with her indicated she was a Spanner (time-traveler). So he of course asked about this, and so she (or rather, his subconscious, played by me) filled in details of how they were being kept apart by her direct superior, Alexander Graham Bell. Yes, that Alexander Graham Bell.
Why was Bell keeping Beverly away from Declan? There's a minor rule amongst the Continuum that Spanners are not supposed to procreate with one another. Imagine a small child with the power to invert causality, or worse yet a baby that can teleport out of the womb. Scary stuff, so the rule is fairly reasonable. Beverly explained to Declan that Mr. Bell, her mentor, was concerned at her obvious affection for Declan, and feared she lacked the willpower to keep things platonic. This is why should could only visit Declan rarely, and on the sly.
To his credit, my player chased after this plotline with gusto. He started up a relationship with Beverly, and would tastefully ask to skip ahead to the next morning whenever they were alone together. Which is something I'm very thankful about, because it means we aren't left wondering what was really going on in any compromising scenes. They snuck around outside of the watchful eyes of The Continuum, made secret dates, and complained about how A.G. Bell was forcing them to be all cloak & dagger.
As GM, I just kept upping the dramatic ante. Beverly eventually showed up (all in Declan's mind) as an Exalted (one of the top ranks of the Continuum) based out of Atlantis (a big floating prehistoric battle platform to protect mankind from the time-traveling bad guys). Or so she said. There were a couple bits that didn't quite add up, and so Declan decided to get Further Information. I believe the player wanted to make sure that his sweetie wasn't a Narcissist (essentially a temporal terrorist), but the in-character motivation was basically to confront A.G. Bell and get everything out in the open. You know, pursuit of maximum drama. :) So he tracks the inventor of the telephone down, and starts interrogating him about Beverly.
"Who?!" Alexander Graham Bell asks. "Young man, I'm afraid I have no clue of whom you speak."
So Declan goes off on him. Lots of in-character yelling, and then a couple sessions dedicated to proving that A.G. Bell was lying to him. As that seemed to fail, he asked some NPCs for help spying on Beverly to make sure she wasn't up to no good. As you can imagine, hiring private eyes to investigate someone who doesn't even exist eventually lead to help of another sort. Some Psyches (time-travelling psychiatrists) caught up with Declan and took him somewhere remote to get some much-needed rest and counseling.
One of the awesome things about a time-travel RPG is that you can advance the plotline or timeline for one PC without it affecting the others. If you were playing some other RPG and one character went nuts, you'd either have to retire the character, or come up with some miracle cure. Instead, Declan spent 3 years in therapy in a Boxed (really really really remote, both temporally and physically) facility, conquering his own inner demons. We talk a bit about therapy, introduce a few NPCs he meets at the asylum, and then, 3 years older and wiser, he spans right back down to just a couple seconds after he left the party. That's a useful tool / implication of time-travel that has never before proven as immensely useful as it did last session. What could have been a campaign-wrecker instead became a puzzle with a quick and painless solution.
Now, it occurs to me there's a lot more I could have done to keep the truth from him. As I understand about schizophrenic delusions, most people inflicted with them go a long ways towards rationalizing and justifying their visions. Anyone who tries to tell them they're crazy stands a good chance of being labeled "part of the conspiracy". But ultimately, that would make this entire campaign a game about how this one PC went nuts. I just recently did a game (3:16) about people going nuts. I didn't want to tank or warp this campaign entirely around it, unless it was really an exciting concept to the players.
So, rather than come up with more convoluted defenses for Beverly (as if "I've been spending time in Atlantis because Alexander Graham Bell doesn't trust me around you" isn't convoluted and ridiculous enough), I decided to just throw things in the player's court. If he wanted the quick 10-minute solution, which he did, it would just cost a couple years of his character's life. If he'd instead told me "No, I want to be like Baltar", then I would have continued to play his imaginary friend on-and-off, but kept it secondary to the plot, just a minor character quirk. In the real world, when you can't tell reality from imagination, it's all but "game over", but this being an actual game, I need to make sure it only enhances the fiction. This may be Gumshoe, but it ain't Trail of Cthulhu, and I feel no need to ride the road to madness and despair in a streetcar named tragedy... at least not if it's not what the whole playgroup thinks would be the most fun. When the insanity is over, the game must go on.
Meanwhile, one of my other PCs is busy having The Last Supper with Christopher Marlowe and Derren Brown, but that's a tale for a whole other blog post some other time...