You best not miss...

Guns don't kill people, murderhobos kill people! Specifically, when they engage ED-209 in a firefight for control of the strategically vital playground in the middle of an oil refinery, and miss.

Below is a random generation table for determining what happens when player characters in a modern or cyberpunk roleplaying-game miss what they're shooting at. The table is designed to be rolled when a character misses a shot with a projectile weapon in a dangerous area. Or a crowded one. Or rolls a critical failure. Or the GM is feeling particularly vindictive. 

The collateral damage table is very much inspired by the Ship Collateral Damage table in the Rogue Stars wargame. It's much shorter, because neon slicked streets lack some of the exciting options for catastrophe a spaceship possesses - atmospheric leaks, artificial gravity failures, that result which causes the ship to burst into flames and kill anyone who can't get to an escape pod...

This table should also be rolled if the PCs leave a loaded gun with a toddler or take lots of drugs before the run or decide to go into a night club with their helmets on and their assault rifles loaded (every Cyberpunk 2020 party has done this, without cause. Every Shadowrun party has done this, as a survival necessity).

The dice rolled varies depending on local conditions.

For a region free of bystanders, roll a D10.
For a region with a few non-combatants nearby, roll a D12.
For a crowded room, a crowded theatre or a crowded crowd, roll, a D20.

The GM decides exactly where in the environment the effect applies. Remember bullets frequently, like, pass through walls.

APPALLING COLLATERAL DAMAGE BELOW THE JUMP:

Roll	Collateral	Description
1	Alarm!	The shot triggers a car alarm, a burglar alarm, a fire alarm, or so on. A loud wailing siren goes off, alerting everybody nearby and seriously impairing situational awareness.
2	Ricochet!	A random combatant other than the target is hit by the bullet. If no other combatants are in a plausible position, the shot simply causes even more collateral damage - roll twice more on this table.
3	Power Out!	The shot hits a power cable, turning off some or all electrical equipment in the room. Specifically, it shuts down anything currently being used in an ongoing skill check.
4	Lights Out!	The lights go out. Unless natural light is available, night fighting conditions apply.
5	Steam Spray!	The shot ruptures a pipe or fire extinguisher, blocking line of sight over a five metre radius. The steam also disrupts lasers, certain sensors and makes anyone caught inside the steam damp.
6	Router Down!	The bullet destroys a wireless router. Depending on the location, access to the net may be lost entirely or wireless devices will have to reset as they find a new connection. In any case, anyone within 75 metres of the router is dumped from their connection. Augmented Reality systems, public access drones and incoming signal guided rockets are all affected.
7	Shrapnel Spray!	The bullet shatters a window, a bottle of acid, a wooden wall… place a metre diameter blast. Anyone within the blast takes light damage.
8	Fire!	A fire breaks out, engulfing a two metre radius within the arc of the shooter. It will likely spread quickly. Indeed, if not put out in a few turns, the area will start to fill with noxious smoke.
9	Electrical Fire!	A fire breaks out, engulfing a two metre radius within the arc of the shooter The fire is electrical and cannot be put out without proper procedures. If not put out within a few turns, the area will start to fill with noxious smoke.
10	Explosion!	The bullet hits a gas tank, the hydrogen fuel cell of a car or a weirdly video-gamey oil drum. Place a blast marker within line of sight of the shooter, causing heavy damage to anything caught within. Roll a D6: 3+ causes a Fire! 6+ causes an Electrical Fire!
11+	Aww Crap!	The attack hits a bystander.

I'm convinced that blaring car alarms will be the defining sound of future urban warfare.