First listen to
@AtomicPope they obviously know what they are talking about and anything inspired by Tremors can only be good.
I was trying to think what I would do. The first desicion point I hit was how to the PCs succeed. Do they have to make rolls to find the creatures or as long as they go into the woods will they cross paths eventually. Then the question is, if it's rolls what happens if they fail and if it isn't how do you make it not be on rails.
I think I'd have the party make some kind of tracking hunting rolls of various difficulty depending on the terrain/situation and modifyers for clever/stupid ideas/looking in the right place for clues to random it up with the idea that some rolls would be passed but some failed and have a handfull of scenarios for both.
E.g. If they pass, they encounter some trail of destruction/dying survivor etc. That would confirm they were on the right path. If they fail they will run into someone/something that would put them back in pursuit. (a bloodcurdling scream from higher up, a bloody animal with claw marks that clearly came from the left before dying etc.)
If say there were four stages each pass scenario could give a clue that would help with the final encounter. Either finding out one of the creatures is injured or some clue about the terrain ahead that would give an advantage in the final encounter or something similar. If they fail and get the back on track encounter they miss out the on the trail scene and the info that comes with it.
Or each failed roll + detour changes the final encounter location. 0-1 fail, catch the creatures on the move- advantage PCs. 2 fails, creatures reach their lair only one way in - advantage creatures. 3 creatures reach their lair have time for dinner, rest and a movie and are fully rested when the PCs finally arrive.
That way the PCs actions matter, there is some randomness/rolls so it's not all on rails and although the fact of a final encounter is preordained there is some variation depending on the PCs prior actions.