I've made the whole system of Hammercalled's threats and other systems into one semi-coherent system now, so I want to talk about how it works and what makes it go well. I still need to write some of this into final game terms, but this should give enough detail.

Danger

Danger goes through the whole game as a measure of difficulty. It's not required to be used for everything (e.g. there's no automatic penalty to being at Danger 4), but it gives a concrete measure of difficulty and also provides a value that can feed into threat mechanics.

Situations

Situations are essentially hosts for threats. They're the equivalent of initiative rolled combat in D&D or other games, but don't need to be necessarily combat oriented.

Situations need a prevailing active threat to be active. If there is no threat, the situation doesn't necessarily vanish, but it doesn't do anything.

When a situation picks up, the game moves into measured time. This doesn't have to be a particular amount of time, but each time the arbitrary turn ends characters suffer the effects of the active threat.

A distinction here is that a GM determines exactly how much can be done between threat activation. It's not divided down into actions. Real time metrics are probably good here

Threats

Each threat is a distinct entity that poses a problem for some or all PCs.

Each threat is defined as having two components: risks and thresholds. They may be further modified by qualities, but that goes down to further levels of detail than I'm going to concern myself with yet, and since a lot of what Threats do can be handled in narrative by the GM it doesn't necessarily make sense to talk about qualities too much. They are simply short-hand for particular risks or thresholds you are likely to see (e.g. a combatant may have the Damage Threshold quality, which means that they need to take X damage in a single hit, rather than X cumulative damage, to be Bypassed or Destroyed).

These may be defined either in terms of game mechanics or narrative events.

Risks

The risk is a challenge that a threat poses. This can take the form of an Ongoing risk and an Activated risk.

Environmental Threat Risks

Environmental threats have two types of risk:

Ongoing risks are a constant penalty that characters suffer or something else; this can be adding a new Threat (e.g. one more enemy shows up every turn), or a penalty due to increased difficulty of actions.

Activated risks happen at dedicated times when a requirement is not met.

In either case, all characters caught in a situation suffer the effects of an Environmental Threat, unless they can Bypass or Destroy it.

Combatant Risks

A combatant's risk takes the form of an attack or action that they do each turn.

Attacks have two values: Damage and Defense

Combatants may also have special actions that replace attacks.

Thresholds

Thresholds are the measure by which a Threat can be dealt with by players.

Thresholds come in two forms: Bypass and Destroy.

A Bypass threshold allows a character to ignore the Risks posed by a threat. For instance, a fire can be Bypassed with a Grace roll, but it will require a concerted series of events to be Destroyed.

This can take the form of a skill roll, damage, or a narrative goal. Environmental Threats that are Bypassed don't impact a particular character, ones that are Destroyed cease to impact anyone. Combatants work differently as described in their section.

It's worth noting that you can have Combatants who don't have traditional damage-based thresholds, and Environmental Threats that can be destroyed via damage, but that's not necessarily worth going into too much detail on here. Think of this for something like a special boss-fight in a video game where you need to accomplish some other objective.

Environmental Threats

Environmental Threats are designed to provide a challenge to players. The All-Environment armor quality provides protection against these and reduces their penalties (by -3 per Protection rating of the armor).

All environmental threats impact everyone equally, unless they are able to get away or use some special ability for protection.

Examples of this could include:

Blizzard Conditions

The extreme cold and snow make it hard to work and can cause characters caught outside to freeze.
Ongoing Risk: -6 to actions.
Activated Risk: Suffer Danger+2 damage from cold every hour.
Thresholds
Bypass: Toughness (0)
Destroy: The weather changes.

Fire

The room is on fire!
Ongoing Risk: N/A
Activated Risk: Suffer three damage per combat turn.
Thresholds
Bypass: Grace (0)
Destroy: -20 with appropriate tool/method to extinguish the flames.

Combatants

Unlike situational threats, Combatants always work by taking attacks against players' characters at the end of a round of combat. If Bypassed, they are removed from combat after doing their attacks for the round, but if Destroyed they do not get to attack. This can incentivize sinking more damage than is strictly necessary into a greater threat, and gives some room for GMs to make interestingly diverse enemies.

Hits are basically independent HP pools; they don't add together but a hit that does, say, 24 damage to the APC would be reduced to 20 by the armor, then that 20 damage would be divided by 6 to give three hits. The remainder is lost once the calculation is finished, but the hits suffered remain.

Each of the different actions is an option for the GM to choose from, so for the APC example below it can either deploy an enemy or attack with its own weapons.

Minions are Combatants who are Destroyed by taking a single point of damage, which is one of the combatant qualities that will find its way into Hammercalled.

Sharpshooter

"I'm going to make you regret coming here."
Standard Attack
Damage: Danger+4
Defense: Awareness (-10)
Thresholds
Bypass: 10 damage
Destroy: 14 damage

APC

Full of angry enemies, this armored vehicle still has its own weaponry to cause problems for the players.
Concentrated Fire
Damage: Danger+6
Defense: Awareness (0)
Sweeping Burst
Damage: Danger+2
Defense: Awareness (+10)
Attacks three targets (never the same twice)
Deploy Troops
Create two Minions who attack for Danger+2 against Awareness (0) each turn.
Thresholds
Bypass: Four hits of 6 damage.
Destroy: Six hits of 6 damage.
Qualities
Armor 4