The First Step

First things first: what's this game about? In some ways this is already answered since we're using an existing game's setting. Shadowrun's a game in which skilled, and often augmented social outcasts perform clandestine missions, usually against and for faceless megacorporate powers.

That's a pretty accurate summary of Shadowrun's premise, but it's not much to work on in terms of saying what the game's about. So I think it best to go broader and examine the fundamental aspects of the cyberpunk genre as a whole. What's core to the genre? What needs to be represented? In answering those questions, I paraphrase John Wick (yes, I read a lot of what he had to say on the matter, you should too): It doesn't matter what your flavor text is in a campaign; if you don't have a mechanic for it, your players will ignore it.

After doing some reading and talking with some of my players, I got the following list:

• Cybernetics - duh, right? Well, not just cybernetics, but specific implants. As in there needs to be rules for specific implants, not just some vague hand wave approach that "you're stronger" or "you're faster." There should be a catalog of implants, and it really should feel like you're shopping for body parts. The dehumanizing elements of advanced technology seemed like a strong undercurrent in much of what I read, and turning your biological makeup into a parts list really punches that home.
• Broken Characters - a player of mine pointed this out to me: characters in cyberpunk stories almost always have something wrong with them. They're on the outskirts of society not because they're all cool and rebellious, but because they've broken in a way that prevents them from living a normal life. Nothing revolutionary here; flaws have been a part of RPGs for decades, but they need to be in this one too. They may even need to be mandatory.
  
• Speed - this isn't so much something that came up in the non-game fiction, but it's a core part of the Shadowrun universe, and shows up in its stories all the time. Speed is key. Samurai are always talking about the edge their boosted reflexes give. There needs to be some mechanic that allows faster characters to get an edge over slower ones, be it simple initiative bonuses or something else.
• Guns Guns Guns - it's a joke among my friends that every time they go shopping in Shadowrun they invariably forget to buy whatever it was that sent them to the catalog and instead buy three or four guns apiece. More than that, though, is that the wide selection of firearms and other weapons allows people to spout off about the particulars of their weapon like a true expert, which actually helps establish character. So, extensive gun/weapon catalog with rules that differentiate them.
• Supernormal Characters - cyberpunk stories, and Shadowrun missions as well, are about a group of specialists who come together to pull off some difficult, covert operation. In a lot of ways they're like high-tech, gritty versions of the superspy story or a heist (think Oceans 11 or The Italian Job). Thus characters, even starting characters need to be better than average, at least in one area. They should be specialists who right off the bat are better than most at their chosen field.
  
• Planning - I noticed something in my Shadowrun games throughout the years. There was a pattern of behavior that showed up again and again. A new group takes a mission and plans for hours on how they'll execute it. Somewhere in the course of things, something goes wrong and they shoot their way out. So, they plan multiple contingencies in order to address this, something they didn't plan for happens, and they shoot their way out. Eventually, the group decides that no matter how much they plan something is going to screw it all up, so why not just skip the hours of planning and go in shooting. After all, everything on their sheet is about combat anyway. It's a logical progression, but not the way I want my games to go. Thus, planning needs to be rewarded or encouraged.
• Contacts - I was very impressed with the use of contacts in Neuromancer, and I never felt that Shadowrun addressed them in a way that encouraged such widespread use as I saw in that book. In fact, unless I gave them out for free, my players routinely skipped them. Something that makes contacts cooler or promotes their use is called for.
• Trust - "It ain't a shadowrun until the Johnson screws you twice." Anyone who's played Shadowrun at all knows that saying. That and "Never deal with a dragon." And yet there is an expectation of playing straight with your employer that appears in cyberpunk in general and Shadowrun in particular. It's okay for a character to seek vengeance on an employer who double crosses him, but if he's the one to pull a fast one, the narrative punishes him. Thus there needs to be some kind of encouragement to play it straight, even if you are playing a criminal.