Chase but on a grander scale.
Always let the player know how far behind the foe is and think of a series of paths that they can take, reward harder paths and DC's with real benefits that are noticeable later or during the chase.
I'm working on a subsystem for the same purpose, a flight from danger over several days or weeks. I'm taking more inspiration from the Infiltration subsystem than the Chase subsystem, since the latter feels more appropriate for short sprints than the marathon hide-and-seek I'm going for.
My idea is to use diminishing VPs to represent the party's lead over their pursuers, with complications arising at different thresholds, representing the rising danger as the bad guys gain on the players, things like encountering scouting parties, the bad guys recruiting spies, and strongarming local authorities into hunting the PCs.
The PCs lose Lead Points by traveling too slowly, leaving a trail, and making too much of a ruckus when visiting settlements. They can regain points by pushing themselves to travel as fast as they can and by forming positive bonds with people in settlements, who might stifle the bad guys' investigations.
You might want escalating scales of failure so that it's not "BBEG caught you and now you're dead or have to ruin verisimilitude to bail you out."
So as their lead shrinks, increasingly strong (or just persistent) enemies begin showing up, obviously part of the pursuing force. Maybe even beginning to cut off certain options until finally the party has to enter the Mines to escape it all.
Or instead of mines (cuz copycat), have a few tricks up your sleeve planted early, like the pendant the party earned for saving the old guy tells the old guy's son (who happens to own a river boat) that the party's worth risking a boat to rescue. Or just when the enemy forces appear to cut off all routes (due to bad dice perhaps) they're told of a secret path by a Dryad they befriended, not earning them escape, but a reset to keep trying.
The difficulty with running a chase (after initial setup) is keeping up the sense of tension (arg, he's right on our heels...) while having some cushion (...and I tripped so now I'm dead.)
Awakening an angry beast to attack the pursuers is a fun win for the party. Cutting down trees, getting past a fragile bridge first, and so forth can all help with the ebb & flow of tension
(I'm reminded of a chase on a smaller scale where the party was meant to flee. They eventually did, yet one guy stayed behind to give the rest some time. Through crazy rolling on both sides (multiple 1s to miss the killing blow followed by a 3x crit w/ 20s pumped up with Domain boosts), that guy killed the BBEG many levels too soon! Maybe I should've had layers of bad guys just to shelter my BBEG!)