The first thing i took out for Fangs, Plagues and Gunpowder was the way heat and complications work. I much prefer systems where the GM knows what shoe is about to drop so you can effectively drop hints and build tension before things break bad. It felt like complications were intended to create a sense that Duskvol is a living place, but I much prefer running a faction turn so I'm not working backwards to justify what the dice told me occurred.
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I made a few tweaks based on how I prep BitD:
During prep I play a solitare game where I write down any factions who are on the PCs radar (or should be!), what they're hoping to achieve, a clock for how close they are, and roll tier to see how things go. The factions in BitD already have a lot of these prewritten which is a great source for ideas. The investigators, bluecoats, or spirit wardens are always investigating someone (especially if the crew has heat), and someone is usually trying to get payback on the crew (usually in the form of trying to track them down).
I try to write down very brief explanations for what happened, especially if a clock fills or a high tier faction rolled really poorly. The Spirit Wardens are Staking Out Your Hideout, the Silver Nails screwed up a job, Lord Skurlock can't get the haunted statue he needs so he's hiring The Dimmer Sisters, whatever. Some of these are News that I can tell the players at the next session. Some of these are secrets that I keep in reserve.
In blades, the secrets are just to give me something to complicate things when players (invariably) latch on to the idea I have the least prepared. Fun BitD GM tip: tell your players its fashion week! They will rob it immediately. Knowing that The Wraiths are trying to steal The Maltese Falcon makes it easy to not only have something worth stealing but also a complication as you bump into each other on the job. Rather than roll for consequences after the action, their behavior might change The Wraith's goal to stealing back the Maltese Falcon, trying to convince a bigger crew to come after you in retribution, or just learning what your deal is and if they should try and broker a peace. For me, its all the benefits of complications without tying anything to heat (which I never have because my players are so heat adverse their hideout doesn't even have a kitchen). If something REALLY bad is coming, they'll learn about it ahead of time and can react.
As I type this, I'm realizing that Cultist Simulator was a huge influence. Weird!
What I'm experimenting with in Age of Beasts (which Fangs, Plagues, and Gunpowder is kind of evolving into) is a Doom Clock that works kind of like Fronts in Dungeon World. Basically you start the session with a couple rumors to follow up on (The Holy Reptile Empire has sent scouts to a nearby village and might try and raid for slaves, a member of your community is suspected of following the Cult of Man, the coyote bandit-lord who rules the area is raising taxes to unreasonable heights and nobody knows why). The PCs follow up one one (or none) of these, and the GM picks an unused one in secret.
When the PCs make camp, they can take as many downtime actions as they want for each action after the first, the GM gets a doom die. When camp breaks the GM rolls and begins to fill the clock, and begins to drop hints as to what kind of trouble is coming. They might bump into a band of fascist geckos mapping the area, that creep from the community might be following them, or you might hit a bandit-lord toll bridge.
I'm still testing this but the goal is to accomplish two things: to create a little more ludonarrative harmony with downtime actions and to build tension during play in a way that makes sense to the players. In blades you can spend coin or rep to do more stuff in town but out on a trail that doesn't really make sense. Also there's no cops which sounds great but means heat doesn't make a ton of sense. Players HATE to give the GM dice to do something bad to them, and it feeds into the sense that the characters have to keep moving before something finds them.
Right now I'm trying to get a better sense of how Trophy raises tension by encouraging GMs to write little descriptions for consequences and tone as they progress. I'm also trying to really narrow the focus of the game - I've found that when players know what their crew is about and how they operate (like in blades) then they actively CHOOSE the job they want, and the threat of complication is more meaningful. In my most recent playtest they kind of just picked what sounded cool, but when another problem started to emerge they were like oh ok lets do that instead. Not exactly the sense of doom I was going for, lol.