Hit Dice Dungeons!

While running Macchiato Monsters the other night, one of my players joked about how we should be tracking hit points with a Risk Die, since everything else in the game uses those.

But then we stopped, thought about it, and realized that it actually sounded like a good idea.

So here's a combat system using only a usage/risk die for tracking harm. It's designed to slot into something like ITO, but I included some potential ways to expand this into a full system at the bottom (or just go use Jason Tocci’s 2400 which is better than whatever I'll come up with).

Hit Dice Combat

Combat occurs simultaneously. Everyone involved declares their intent for the turn (usually moving a short distance + attacking, taking an action). The GM declares NPC actions first, but everything is resolved simultaneously.

Attackers do not roll dice to resolve attacks, instead every attacked creature rolls their Hit Die to avoid harm for each attack.

If the Hit Die rolls a 1-3 (the Threat Range) the Hit Die steps down in size. If the die cannot step down (i.e. it's a d4) the creature is incapacitated. They're bleeding out and will die in an hour if left unattended.

Armor and Weapons

Deadly attacks expand the Threat Range (e.g. if attacked with a +1 Sword take harm when rolling 1-4). This is written as +X, where X is the amount the Threat Range is expanded.

Armor shrinks the Threat Range, written as -X where X is the amount by which the Threat Range is reduced (e.g. wearing Scale Mail (Armor -1) means you take harm only when rolling a 1-2).

The Threat Range cannot be smaller than 1.

Example Items

Poison, apply to a weapon for +2 to the next attack.
Great Axe, two handed, +1.
Firebomb, blast, +1
Crossbow, slow, +2

Chain Mail (Armor -1)

Helmet (Armor -1)

Plate Armor, bulky, clumsy, (Armor -2)

Shield, sunder to prevent stepping down Hit Die when hit.

 (This doesn't read wonderfully. Positive numbers always increase the Threat Range, while negative numbers always decrease it. However it's sorta messy that +1 on weapons is good, but +1 on armor would mean it's easier to hit you.)

Healing

If you took harm during a combat, a few minutes and a drink of water lets you roll the Hit Die. A result of 4+ will restore one Hit Die level (e.g. d6->d8). This only works once per combat, and only if you were damaged during that combat.

Resting overnight with food and drink automatically restores one Hit Die level, then you may roll to restore a second level (as above).

Your Hit Die cannot exceed its original size through healing.

Example Enemies

Goblin Guard, d4, Dull Stick -1
Lizard Bugcatcher, d6, Spear, Net Throw +1 (On hit tangles rather than reducing Hit Die size)
Fungal Warrior, d6, Spore Cloud +1
Giant Toad, d8, Thick Skin (Armor -1), Tongue +2 (On hit the target is grabbed and swallowed).
Crystal Mimic, d4, Fragile (Armor +1), Shard Stab (+2 if attacking from hiding)
Iron Golem, d10, Iron Construction (Armor +2), 2 x Pneumatic Fists +2
Werewolf, d8, Bite+2, 2 x Claws +1, silver weapons force Hit Rolls at disadvantage.

Ideas for Expansion

Death and Dying

Look at the final Hit Die roll to see what happens when someone goes down:

1: Dead
2: Bleeding out with minutes to live.
3: Bleeding out with an hour to live.
4: Knocked out.

Morale

Roll an NPC’s hit die for morale, on a 1-3 they flee or surrender. Enemies roll Morale whenever their Hit Die steps down (in addition to the usual times). This is basically just how Macchiato Monsters morale works.

Everything’s a Hit Die!

Treat any risky thing as an “attack”. Expand the Threat Range (as with weapons) if it’s particularly dangerous or difficult. Equipment acts like Armor does and reduces the threat range. Rolling inside the Threat Range means failure or harm, rolling above it means success or avoiding the harm.

This has the benefit of folding the entire game into a single mechanic, and means characters are just one die and some equipment.

A downside to this is that reducing the Hit Die doesn’t always make sense for every risk. This could be solved by making failure consequences more diverse when out of combat (or even when in combat!). Reduce the Hit Die when the thing at risk is bodily harm, but other risks could be lost or broken equipment, being separated, being put into a bad position, or really anything that makes fictional sense.

Another downside is that this will tend to make characters death spiral, because they’re entirely represented by one dwindling die. Every failure makes future failures more likely.

More Hit Dice?

Characters have the Hit Die as described above, which represents combat prowess and physical durability. They also have a Skill Die (representing training, talents and dexterity) and a Will Die (representing mental fortitude and magical aptitude).

Use these dice as described in the previous section, but now there’s more flexibility and characters are less likely to death spiral since harm can be spread out.

This also gives a little bit of room for mechanically distinguishing characters.

Advantage and Disadvantage?

It’d be very easy to add Advantage and Disadvantage to this. A clever attack from a good position means the enemy must roll their die at disadvantage.

However, that’s an extra mechanic and this is already something you could handle by giving situational bonuses and penalties to Threat Ranges.

Parting Thoughts

This is entirely unplaytested, just a neat idea I wanted to poke at for a bit. I’d welcome anyone’s thoughts on it, or if anyone has seen it show up in another system.