WARNING: Heavy spoilers for Brainscan.
To some degree, this is inevitable. In order for the next thing to happen, the next thing needs to happen. But when you take these events and play them out in a living campaign, it makes for some pretty dubious adventure design. There's a point near the end where the PCs have just emerged from cyberspace and have every reason to believe that Deus is trapped on a hard drive. While they are still getting their bearings, some Renraku loyalists (specifically the scientists who helped create Deus in the first place) barge into the room, grab the drive and basically go "thanks for the assist, we'll take it from here" but like in a really mean and rude way (the exact dialogue ends with Sherman Huang shooting the body of the late Renraku CEO, dropping a gun into the lap of one of the PC's NPC allies, and saying to one of his lackeys, "if they're smart, they'll lay low and keep their mouths shut. Otherwise they'll have an entire megacorporation after them for kidnapping and murdering a CEO.")
Maybe it's a personal hang up where I get irrationally angry at smug bullies, but my finely-honed GMing instincts tell me that this is a prelude to a fight scene. I figure, 16D stun damage from dumpshock or not, if any PC is conscious enough to witness this denouement, they are conscious enough to unload a clip of automatic fire at the traitors. Even in a perfectly static story like a movie or a novel, Ronin would have picked up the gun Huang tossed in his lap and put a half-dozen rounds in the hard drive. Or, at least, he would have if I were writing it. Some evil scientist is walking away with the AI that killed and tortured thousands of people, and maybe you're not strong enough to stop them, but you can sure as hell ruin the data.
So it's a little weird that the book treats this as just an inevitable part of its climax. "Any attempts to pursue them and retrieve the Mousetrap will be difficult. . . the arcology will be bursting with rampaging drones, escaping residents, shell-shocked Banded and invading military troops. This chaos should be more than enough to distract and confound any pursuers."
I don't know, though. It seems like all of that would be more of an obstacle for a bunch of corporate executives and data scientists than it would for a team of hardened mercenary criminals.
Although, maybe I'm just running afoul of a mismatch between genre and medium. Deus' original designer (apparently) walking away with his source code, stealing credit for saving the arcology (when it was actually the PCs who rescued him from Deus), and being ideally positioned to be promoted to the next CEO of Renraku is a classic bleak cyberpunk ending. Terrible things have happened and the rich people responsible for them will not only escape justice, they will thrive, whereas the working schlubs who cleaned up their mess will have to live in fear. Because everything they did to save the day is potentially blackmail material and it's only a matter of time before the powerful will want to clean up that loose end.
It is perhaps a fitting comeuppance for Huang that Deus isn't actually in the hard drive. He used his vast intellect to reprogram the purge routine and download himself somewhere completely unprecedented. But whatever satisfaction there is in this ending (and it's not much, because Deus is awful) is undermined by the fact that there's no way for the PCs to see it.
This is another case of a medium informing a message. The double-twist is only communicated in the book, not the game (though it's sure to come up in a future book because the metaplot must march on) and even if it were, how do you make a game out of "your actions were ultimately pointless, the villains will just start up their work exactly where they left off, the system will always protect itself?" I want my players to look me in the eye and say, "Thank you, John, that story we told together was cynical and miserable and ended on the perfect downer note. We were all really impressed by the way you absolutely sold our lack of agency." How do I do that?
Maybe I should run Brainscan in Chuubo's . . . Genre XP Action: Take a beat to experience despair at the unmanageable vastness of your own socioeconomic context.
That was, of course, a 1% joke, but it touches on something I think is important in rpg design. Successful adventures are rewarded with treasure and xp, but there's often a more powerful intrinsic reward in simply completing the adventure successfully. And this works out great in genres like epic fantasy, space opera, and 4-color superheroes. The players are fighting their hardest to make a happy ending, but so are their characters, and so is the world. Star Wars is supposed to end with the defeat of the Empire. But there are other types of story to tell.
In a cyberpunk story, the characters are fighting just to survive and may feel a certain degree of terror at the prospect of being responsible for a happy ending because such things are not supposed to be possible and the world will punish them for challenging the system. But the players in a cyberpunk rpg still have that fundamental rpg instinct. They are trying for a happy ending. Not necessarily consciously. I'm sure there are a lot of Shadowrun players out there who, if you asked them if they'd prefer for Brainscan to end with Deus destroyed, Sherman Huang facing justice, and Renraku having its charter stripped and its assets seized as reparations to the arcology victims, would say, "no, obviously not. That's not remotely the setting I signed up to play in." And yet, when the time comes, that belief will be nowhere near strong enough to stop them from fighting to get the Mousetrap back.
So how do you make getting bushwacked by your money-grubbing erstwhile allies feel like a reward? How do you make the bleakness and the futility feel like a successful conclusion to the story?
Shadowrun's solution is to not even try. Whenever the story needs a betrayal or a setback, the event happens, regardless of what the PCs do. For example, earlier in the story, the PCs are present when Deus' minions try to capture Sherman Huang. "If the Banded are driven off without capturing Huang, they manage to do so a short time later." And I can't really disagree with the approach - I find it best when things that the PCs are going to object to happen off-screen - but it makes me a little uncomfortable to tell a story about the characters lacking agency by making sure that the players really do lack agency.
Now, forget everything I just said, because there's another perspective - if you, as a GM, are good enough at selling the highs and lows, then a lot of the time the players will experience a railroad as a rollercoaster (i.e. fundamentally the same thing, but really exciting). There's an art to it. You can't ever let the players know you're cheating, but you do it by hiding your cheating in the ambiguity of their blind spots. Then, when the unavoidable thing happens, the reaction is not "this would have happened no matter what," but "oh no, why didn't we think to cover that blind spot." There's actually a good example of that in this adventure. Deus needs to track the PCs to a certain location and the book suggests several ways he could do that. The method he uses is always going to be one of the ones the PCs think to look for plus a redundant back-up plan that uses one of the ones the PCs overlooked.
(Sometimes you get a group of players whose take away from these tricks is "we should be hypervigilant and spend a long time at the table trying to cover every contingency" but that's really a sign that you're playing with a group that would prefer a sandbox).
Overall, I think Brainscan is a fine set of adventures, but if I ran it for a group, they would almost certainly break the plot. Which isn't even remotely a flaw in most adventure modules (because they would otherwise need to be 1000 pages long to cover every possible contingency), but does give me pause in the context of Shadowrun because I just know that the conclusion to this metaplot-driven adventure is going to be the setup for the next metaplot-driven adventure and it's a weird sensation to realize that you're inevitably going to obsolete a book that hasn't even been written yet (c. 2000, my understanding is that System Failure picks up where this one left off).
Ukss Contribution: One of the intrusion countermeasures in Deus' ultraviolet server (a Matrix environment indistinguishable from the real world because it's a weird setting premise that the most computationally intensive processes take place in high-resolution metaphors) is a nest of chromatic snakes. The book doesn't go into as much detail about these creatures as I'd like, but I thought it was a neat image.