Welcome to the Deathtrap: TTRPG Rules Hacking in Action

Image by PIR04D from Pixabay

I thought it might be helpful to give an example of a rules hack I did last year that I was particularly proud of as a follow up to my four posts on rules hacking and customization. The previous ones are:

And I wrote my recent review of Blades in the Dark as a lead-in.

Picture This...

This is from an ICRPG Core 2e fantasy campaign I ran in 2020. It was, by this time approaching 140+ hours and 34 sessions into the game.

The PCs are mercenaries hired by a merchant-prince to equip and train bronze-age shepherds with 14th century weapons and Armour so that they can defend themselves from an invading tribe of cannibalistic Demon worshippers who've built hidden war camps in the unsettled bush around the shepherds' lands.

The PCs are leading a green militia on their first foray against one of the invaders' war camps. Just as they are an hour out from striking distance, their advance scouts learn that the encemped war-band is striking out towards a village about five hour's wak away., leaving only enough guards to keep the invaders' captives in line and prepare for the return.

The PCs wait two hours then strike, letting a few escapees to alert the main enemy force of the attack. This gave the PCs several hours to prepare an ambush for the returning invaders.

The PCs have significantly smaller numbers and mostly green recruits, but better technology and time to prepare. Not to mention tactical acumen & exotic magics.

The Problem

Pacing was a major issue with the campaign at the time. After several sessions of diplomacy, intrigue, and training, I needed the game to keep moving. I'd had players say that they loved the campaign, but needed some mayhem and carnage or they would rather take a break from the game. And they were being perfectly fair.

If the PCs wanted an effective ambush, I would have needed to give them a map a record of their troops, some markers, and probably 40-60 minutes of planning. And the momentum would be dead. I had identified a gap in the rules I was using that needed to be filled.

I needed a set of rules that would let the players have the benefits of planning a meticulous ambush without actually using half a session to plan a meticulous ambush... And I needed them fast. It was time to do a hack on the fly.

I had a beloved NPC utter a dramatic "Let's make sure they come home to a warm welcome." then called for a bio-break.

Revisiting My Vision

So, before I hacked anything, I needed to remind myself of my vision for the campaign. So, for reference here is my Poster Pitch for the campaign. (In this case, the PCs

She Who Waits...

A Mysterious and Intrigue-filled Fantasy Saga for ICRPG 2e

She who waits is a tale of young people who discover they are part of a noble house in exile when have to fight for their lives to escape enemies who would kill them over old feuds they have never known. To survive they must make allies and claim their birthright by their wits and by the sword. Focused on Dominion-level play.

Inspiration
Film & Television: Game of Thrones, Return of the King, Excalibur
Video Games: Final Fantasy Tactics, Banner Saga, Final Fantasy XII, The Elder Scrolls IV: Oblivion.
Books: Nine Princes in Amber by Roger Zelazny, Oathbound by Mercedes Lackey, Arrows of the Queen by Mercedes Lackey

I need to ensure that any modifications I make support an air of mystery and intrigue, and feels like a Saga (I.e. The tale of a few people whose choices and deeds shape the fate of a people.)

I also want to revisit my watch words for hacking, which are: Fast and Simple.

Grabbing a Useful System

I could not think of a system that could easily allow me to gloss over planning that was similar to ICRPG, but I recalled that Blades in the Dark has several systems that were designed to accelerate planning for heists.

I grabbed the flashback rules from BitD from the Forged in the Dark SRD:

Flashbacks
The rules don’t distinguish between actions performed in the present moment and those performed in the past. When an operation is underway, you can invoke a flashback to roll for an action in the past that impacts your current situation. Maybe you convinced the district Watch sergeant to cancel the patrol tonight, so you make a Sway roll to see how that went.
The GM sets a stress cost when you activate a flashback action

0 Stress: An ordinary action for which you had easy opportunity. Consorting with a friend to agree to arrive at the dice game ahead of time, to suddenly spring out as a surprise ally.

1 Stress: A complex action or unlikely opportunity. Finessing your pistols into a hiding spot near the card table so you could retrieve them after the pat-down at the front door.

2 (or more) Stress: An elaborate action that involved special opportunities or contingencies. Having already Studied the history of the property and learned of a ghost that is known to haunt its ancient canal dock—a ghost that can be compelled to reveal the location of the hidden vault.

After the stress cost is paid, a flashback action is handled just like any other action. Sometimes it will entail an action roll, because there’s some danger or trouble involved. Sometimes a flashback will entail a fortune roll, because we just need to find out how well (or how much, or how long, etc.). Sometimes a flashback won’t call for a roll at all because you can just pay the stress and it’s accomplished.

If a flashback involves a downtime activity, pay 1 coin or 1 rep for it, instead of stress.

The rules in this subsection are CC-BY One-Seven Design

This can serve my purposes perfectly. Players can use Flashbacks to handle positioning the special units, setting traps, making barricades, establishing signals, etc., to cover their prep on the fly in response to events on the battlefield.

Making it Abstract

Taking a step back from the specific mechanics of Forged in the Dark, we can rephrase the rules like this:

When an encounter is underway, characters can Invoke a flashback to have the character have previously made an action in the past that impacts the current situation. Maybe you positioned your archers on the cliff or set a trap that could be set. These cost a variable amount of a limited resource, that may harm the character if overdone.

The more sophisticated the action, the greater the cost in stress.

After the cost in resources is spent, the action is handled just like any other action. Sometimes this will entail a roll, because there is some danger or risk of failure involved. Sometimes a flashback won't call for a roll at all.

Aiming for Reasonable Unity

So how do I make this work in Index Card RPG Core 2e? Well, what I really needed is a resource that they can spend to mirror the subsystem. ICRPG doesn't really have a good equivalent to Stress except the one-at-a-time Hero Coins, and they have no consequence to being used up. What ICRPG does well, though, is countdowns and giving tasks a hit-point value.

So, I decided that I would give the PCs a one-HEART (10hp) "stress" meter for flashbacks. Anything that would cost a PC a few minutes of time and effort (equivalent to 1 stress above) would cost 1d3hp to the counter, or 1d4 if it was particularly taxing (2 stress). This mirrors the Effort system already in play in ICRPG. I can apply overflow to their acual hit points.

It would probably require fine-tuning if I wanted it to work all the time. (2 HEARTS would make the math feel closer to BitD.) but given that this is worth about a 4-hour window of opportunity and not Ocean's Eleven, it works just fine. I have a good enough system for my purposes.

Being Transparent

All of this was done in the time of a bathroom-and-coffee break. When the players sat down again I gave them a clear rundown:

"Listen: we have great momentum tonight, and I don't want to break it with a long planning session and drawing huge maps. Here is how we are going to keep it moving. I am going to fast forward to the battle. I am going to assume you set up a bunch of clever tricks for an ambush.

"So, I am going to give you one HEART each that you can use to flash back about things you prepared. So, if I say there is a group coming around the pit trap, and one of you wanted to add a trap of your own on the safe path, then you can say: 'hold on, I want to play a flashback.'

"Then you tell me what you did. If it needs rolls, we will roll it. You will lose 1d4 off your Flashback HEART. If you spend more than you have, the rest goes off your hit points, because you tired yourself out with all the excess prep work."

Does it Work with my Campaign?

Lots of Sagas contain tales of clever heroes who did a lot of advance prep to outfox a more powerful enemy, it works in the genre. Certainly, this mechanic could be useful in setting up intrigue as well in the future, as it allows you to go into meetings with your eyes open. I feel it absolutely serves to speed up play, which I needed that night. I worry that it might kill mystery, and so I would only use it conditionally in certain situations.

So, How Did it Work Out?

It was a slaughter! As the enemy closed in, tiger traps dug by the apprentices of the group's mage forced the enemy into a narrower choke where they found caltrops slowed their advance, letting the superior range of the crossbows take out the front ranks.

Snipers and piled boulders let them turn a retreat into a box canyon into a bloody kill-zone as the enemy pursued. And magical scrying tunnels set up ahead of time let the enemy mages be struck with counter-spells from safely behind the lines. A group of fast spearmen were even in place to mop up stragglers.

The players loved that they could do their planning on the fly and still get the same lethal ambush they would have taken hours to create, and the energy in the room never died down. It was a really popular hack.

I hope this example makes me last few articles clearer and easier to put into practice,