I'm using Fronts from Dungeon World, with a little Night's Black Agents thrown in. Players initially just wanted to be treasure/monster hunters but after about five levels of that they decided a little BBG action would help, so long as it wasn't too railroad-y. So I set to work designing it. And plopping it down in the world. Realizing that nothing exists until the players brush up against it. Which means I can add, delete, alter and amend to my heart's content until they're actually in media res. Which is what I've done. One over-arching BBG. Four (was six) factions struggling for dominance. I gave the PC's an artifact and some clues to figure out it's workings. While they searched for that I brushed up the factions. LAST session they FINALLY figured it out and that sets the ball rolling.
The Five Great Prophecies. Each foretells the rise and triumph on one of the factions.
June 21. A generic bard was contracted to journey with the party as the revisited an old battle field. Our ranger had been hired to do away with some marauding bears, which he did. Leaving the rotting carcasses of the large carnivores behind. Which attracted a LARGER carnivore. A green dragon. The dragon was soon dispatched. The bard had his song. AND knowledge of the artifact. Five days journey found him back in the capitol city. There he reached out to the House of Pellissi, patrons of entertainers known to pay for information. A quick visit to the School of Illusion netted him a bit of a disguise to protect him from feared retribution.
House Pellissi ALWAYS seeks favor from House Lupine, and with the election only six months ago it was important to keep ties intact. The School of Illusion took longer to pass on the news - always on the lookout for false news dontcha know. Eventually word filtered up to the Archmage. It was going to be an interesting summer.
The Arcane Eye moved first. Valen the Enchanter reached out to their contacts in the "knowledge" world: libraries, scholars, sages and artificers. They were to be on the lookout for anyone seeking information regarding The Compass. (Game-wise: this started the countdown clock to their first Grim Portent. Time now became a growing issue for the party ,although they didn't know it yet.)
House Lupine sent word to Lady Elara who then presented it to the Counsel of Sovereigns. The CoS is far reaching and slow moving. Already mid-July and they have not yet reached a consensus on what action to take. By the end of the month they will have opted to merely consolidate their holdings and grow: More caravans. More thieves. Guildmaster Thaddeus and "The Whisperer" will have a busy summer.
The Circle of the Silver Moon has already made an unauthorized direct attack, sending an Invisible Stalker after Dakora the Enchantress of Fire & Ice. And acid. They need to SERIOUSLY re-evaluate.
The Cult of the Shadow Moon is more circumspect, taking a "wait and see" attitude.
The party sits at July 13 just off the Southern Road, a few days from Crossroad #1. Completely oblivious of ANY of this.
Next Session:
gets us to July 15. I've stripped out one of the factions. No more Shadow Moon. The Shadowmaster (an outlaw gang) has knowledge they'll pass on to The Whisperer. And a stray half-elf ranger will pass word on to The Purple Rider. Arcane Eye is seeking someone to obtain the prophesied grimoire. Dawn's Nexus? They parties foil? Circle of the Silver Moon changes their focus to Brethemney and the blight. The Counsel begin placing new faces in ever higher places.
another few sessions have passed. Today is June 19th, and it's July 25th in the game world. Was NOT happy with the way things were flowing (and neither were the players.) Prohecy's learned weren't sparking interest. The "other stuff" was happening but PCs weren't learning about it since they've opted for a long (productive) trip in the wilderness. So I've fallen back to another old source: "Creating Epic Campaigns" by Guy Sclanders. Have stripped out another faction. Currently have four: the BIG BBG and three "secondary" factions, two of which are functioning under/beside the BIG BBG and another which MAY turn out to be allies of the PC. I've redesigned all of the factions to fit the CEC format. Only one of the prophesies has been "learned" so I'm rewriting the rest to fit the CEC model. Should be MUCH more actionable. It's also helped to design the countdown clocks that will "run" the factions. And taking a page from Gnome Stew to provide a war room for the party. Need to design a polar area chart so the PCs can SEE the progress (at least graphically) and rework the countdown clock. Every iteration makes things a bit clearer.