Demon City will be pretty rules-lite, but I've given some thought to how the rules it does have will be presented.
The rules themselves will be on the left-hand pages of the book, notes on the implications of these rules (asterisked here) will be presented on the facing pages.
As in most tabletop RPGs, Demon City proceeds according to a simple scheme: the Host describes the situation(s) the characters are in, the other players say what their respective characters try to do. When failure might have interesting consequences*, the rules and dice get involved.**
Simple example: Marty might come home late and drunkenly fumble at his apartment door lock before getting the key in, maybe even dropping the keyring in the process. But eventually he'll get it open, so there's no need to roll dice...
...unless (whether or not Marty knows it) Marty's brother is lying on the other side of the door about to bleed out. That's when you'll want to roll some dice.
Basically, for most tasks, the player rolls a d10 and the Host rolls a d10 and if the player gets a higher roll, the task gets done, if not it doesn't and some consequence of failure ensue.
There are some hitches, though:
-There are many cases where the sides roll multiple d10s. Their official roll for the purposes of deciding the contest is whichever of their rolls is highest. So if you roll a 6 and an 8, your "roll" is 8.
-All character stats are ranked from 0-9 (or possibly more, with no maximum, if the supernatural is involved), high numbers are good. If two characters (player's characters or a player's character and an NPC) are competing at a task (say, in a footrace) then whichever has the higher stat gets to roll an extra die. This extra d10 is called the Skill Die.
-Likewise, for tasks where characters do not directly compete (Marty trying to pick an electronic lock, for instance) all tasks are ranked in difficulty from 0-9 (or possibly more, with no maximum, if the supernatural is involved). If the stat number is higher than the task difficulty number, the player gets to roll an extra die and use the better of their two rolls (the "Skill Die"). If the task difficulty number is higher than the stat, the Host gets to roll an extra die.
-Having the Host roll even for the difficulty of dealing with inanimate objects (opening a lock on time, locating a file, climbing a wall) tends to personify the environment--the electronic lock is programmed by someone and Marty's attempts to crack it are against the skill and effort put in by that programmer. However, when there is no way to imagine any animate force actively resisting--like in the example of Marty drunkenly scrabbling at his own lock with his own key--the Host can just assign a static difficulty number to be rolled over (player must roll over a 3, for instance). Recommendations of when to do this and what the numbers should be come later, but just to nail down the basic system, know that the the opposed roll is usually preferred.
-If a task targets someone who is distracted (pickpocketing someone who is watching a car crash happen, for instance) the perpetrator also gets an extra die (the Distraction Die).
-If a task has some other outside factor introduced that makes it more likely one side will win (if someone has a head-start in the footrace, for example) then that side gets another d10. This extra die is called the Situation Die. You can have up to two Situation Dice representing distinct advantages (ie two advantages that would, individually, still be advantages without the benefit of the other advantage--like a headstart in the footrace plus your opponent is running over uneven ground).
-Generally, external problems which make the task harder (like Marty being drunk while trying to open the door) are worked into the difficulty number of a task, but if there is some reason they can't be or haven't been already, the Host may subtract up to two Lost Dice (down to a minumum of one rolled die) to account for problems.
-This all gets more complicated in situations when different characters are trying to do different things that all affect each other at the same time. Combat is the most common situation like this but it could also apply to, say, trying to fix a radio antenna before a metastasizing Crysoloth destroys the building it's in. Like most games, Demon City has special rules for that...
Action Rounds: Slow Motion and Clashes
Like in most RPGs, special rules are used to resolve action. A footrace isn't "action" as defined here because the competitors usually aren't interfering with each other. A car chase can be, though, because cars can cut each other off, knock each other off the road, etc. And combat is always action.
I'm going to describe combat using some D&D terms here because this is a D&D blog so you probably get it--and it'll be faster than describing it from the ground up the way it'd be written in the final book. Basically, there's no initiative but there are rounds. Action's generally going to be over in fewer rounds than D&D, but each round takes a little longer. If it's necessary to know, rounds take about 6 seconds of activity.
This action system is based on "Clashes"--the most important difference between a Clash and the combat in a D&D round is only one party in a fight can succeed at a time. You shoot or are shot, punch or get punched, etc. Though you could succeed at other tasks: you could successfully pickpocket someone and get punched, if you're shot, you don't get to shoot back until the next round (assuming you live).
This is also one of those systems where everyone announces what they're going to do before the first person actually starts to do it. This is slightly less intuitive than resolving an action as soon as it's announced (the D&D way), but I think there's a payoff in that it more closely reflects the fast-but-tense way combat works in horror and crime fiction.
When the Host announces you've entered Action Rounds:
Slow Motion Phase
Whatever entity involved has the lowest Agility (Ties are decided randomly) announces what they plan to do. This can't be an if-then, they gotta decide. (Actions can normally only target one foe at a time--exceptions will be noted when we get around to specific abilities and weapons.)
The Host can begin to describe everyone noticing this slowpoke getting ready to do whatever they're going to do--as if everyone is watching slow motion.
Second-least Agile creature announces next, then the third-least Agile, etc. until they're all announced.
Any action that couldn't interfere with anyone else's action (ie the order in which it happens doesn't matter) is resolved, using the Task rules above if necessary--and narrated.
(For example: Agents Pfister and Foreman are on a two-story roof trying to punch each other, and Lieutenant Hyder announces he is trying to get away. Since nobody named him as a target and he has no target, nothing Hyder is doing will affect who punches who first or hardest, so Hyder gets away. If Hyder had announced he wanted to escape by jumping off the roof, then Hyder's player and the Host just roll off-Agility vs a difficulty number decided by the Host--to land safely on the ground.)
4-Everyone else now collects dice and rolls--this group of competing attempts to do things first is called a Clash. Everybody involved in a Clash rolls d10s at once, as above under Task Resolution, with a few clarifications and special rules:
- Actions in a Clash don't have to match to be opposed--Pfister can being try to punch Foreman and vice versa, but Pfister can also try to get away from Foreman. In a Clash, everyone involved rolls on the Stat they themselves are trying to use. Foreman can roll on her Martial Arts stat while Pfister rolls on her Sport: Running stat to get away. Whoever rolls best does their thing first.
- Anyone taking an action that targets a foe that does not resist that specific action (usually because they're dealing with someone else) or against a foe who is not trying to resist all hostile actions in the Clash (by, for example, fleeing), gets an extra d10, the Distraction Die.
- As with simple Tasks, whoever has a higher stat than all foes they are using their skill to interfere with, attack or avoid gets to roll an extra die--the Skill Die.***
- Anyone with a situational advantage (high ground, etc) over whoever they're directly facing off against also gets an extra die (Situation Die).****
- Another Situation Die is also available to anyone if the character has a second distinct situational advantage on top of the first one. Like their target is both tripping and is handcuffed. This die is also used if someone is attacking (or parrying) with a weapon that is better in the specific situation than the one their opponent is attacking or parrying with. For example, if two characters are fighting under a twin bed, the combatant attacking with a knife or claws will get a Situation Die against a target using a longsword (which needs more room to maneuver), but in most situations it'd be the other way around because the sword has better reach. And all of them would have a Situation Die over an unarmed combatant. This is the main way weapons are differentiated in Demon City (and in horror films)--by the situation in which they are most useful.
- Nobody in a Clash can get more than 2 Situation dice.
- Anyone who has taken at least one injury during the fight loses a single die (the Lost Die for Injury)--down to a minimum of one die.
- Other external difficulties in the situation not otherwise accounted for (by, for example, someone directly opposed already having gained a Situation Die) can be accounted for by Miscellaneous Lost Dice.
- Nobody able to act in a Clash can lose more than 2 Miscellaneous Lost Dice this way or go below a minimum of one die.
- So the maximum dice anyone could roll would be 5: A d10 to start + 1 Distraction Die + 1 Skill Die + 2 Situation Dice + no Lost Dice.
If a successful action involves damaging another character:
- With most weapons, the attacker rolls damage as follows: They take a number of d10s equal to the target's Base Toughness, roll and take the lowest, and the target subtracts that number from their Current Toughness. At Current Toughness -1 they are out of the fight and roll on the Injury table (that'll be in a later entry). So if you have Base and Current Toughness 3, someone shooting you would roll 3d10, take the lowest, and subtract that from 3.*****
- Some few weapons (supernatural abilities, high explosives at close range) do Massive Damage. In this case you roll one die for each point of the attacker's stat and take the highest.
- Kevlar and other protection raises your Base Toughness for these purposes.
Ties after first place also result in temporary stalemates with the Host changing the situation, but only in such a way as to affect the characters that tied and those rolling lower than them in that Clash.
7-Anyone who is present, out of the fight, still alive, and who needs to roll on the Injury table because their last roll wasn't conclusive does.
8-If characters are still involved in Action after all that, start over at 1 above.
Notes I'd put on the facing page:
*Note that failure doesn't have to have predictably more interesting consequences than success--just consequences that are also interesting.
**As in many other games, dice also occasionally get involved when the Host (or even a player) just thinks it would be interesting or more fair to introduce a random element into a part of the game they normally control. For example if a player steals the first car they see, the Host might randomly roll to see what kind of car it is.
***It's possible more than one Skill die gets handed out to opposing sides this way if a fight is sufficiently complicated. For example:
If Alfie (Firearms: 9) is trying to shoot Betty (Firearms: 5), who is trying to shoot CeCe (Alfie's friend, trying to flee with Agility 1)), both shooters have a higher stat than their targets, and Alfie and Betty will both get a Skill Die despite being on opposite sides and despite Alfie being better at shooting than Betty. Alfie will, however, get a Distraction Die (see above).
So if he and Betty try to shoot each other, he gets a Skill Die and she doesn't. If Betty targets CeCe, both Alfie and Betty get a Skill Die but Alfie gets a Distraction Die too, keeping him at least one up on Betty, all other things being equal.
****The value of this extra die means that combat in Demon City will involve a lot of players and Hosts discussing what does and does not constitute a situational advantage. This is good. This is what the players should be doing: talking about the fictional situation as if it were real so everyone is imagining the same events as much as possible and making interesting decisions about how to use the situation. More than one of the entities involved in the Clash can get this Situation die.
*****Humans generally have a Toughness between 0 (feeble pensioner or newborn baby) and 5 (world-class athlete), if you're wondering how long these fights last. The actual negative number past -1 doesn't matter, so any successful hit on someone with 0 Toughness puts them in the Injured box.