The heroes are on the run and flee into the forest, with the pursuing party right on their heels. Every PC needs to reach the goal before the Round Limit expires; those who don't are caught. Since that could split the party and make the adventure rough to run and play for a time, you may choose to have PCs who fail take an Injury or two from the pursuers but still ultimately escape.
Challenges are a bit lighter than normal due to the existence of the Round Limit and requirement that every PC make it out in time.
D (start) / \ A - B ~ C F (goal) \ / E
|(Region A) Edge of the Wood|
|You've reached the relative safety of the branches and brush, but there's no time to stop to rest. There's an old trail here you can follow, but it's not in the best of shape.|
|Ant Swarm||Does not pursue|
|(Region B) Obscured Path|
|Thick foliage obscures the trail you were following. You'll have to dig around to find the right way to go, but with your pursuers so close, there's no time to be methodical about it.|
|Rainbow Moths||Does not pursue|
|(Region C) Fork in the Trail|
|The trail splits here, one direction heading northward and the other veering south. Thick brambles with poisonous thorns have grown over the north side, which will slow your progress. The south way doesn't look much better; it slopes down into a wide, muddy creek.|
|Northeast||D||Wall of Foliage|
|(Region D) Thicket|
|The trail is almost totally gone here; you're essentially having to forge a new one at this point.|
|Southeast||F||Wall of Foliage|
|Southwest||C||Wall of Foliage|
|(Region E) Muddy Trail|
|The wet, sludgy ground slows your progress considerably. Ahead it slopes back upward again, but with muddy boots it'll be a bit tricky to get up there at the speed you need to be moving.|
|(Region F) Above the River|
|You've run out of flat ground! A cliff ahead looks at first like a dead-end. Peering over the edge, you see a river down below. There's also a winding, narrow path you could take down the cliff, which would probably be slow going. But if you're desperate, you could risk a jump and pray you make it…|
|Jump||Goal||Leap of Faith (Height 4)|
|Northwest||D||Wall of Foliage|
The PCs get away safely (apart from any Injuries acquired during the escape).
One or more PCs are caught. If you don't want to split the party, have the caught PCs get away but suffer a couple Injuries from a brief scuffle, flying arrows, or whatever is appropriate based on the particular pursuer. Otherwise, have a plan to reunite the PCs, either without running any additional scenarios, or after a single scenario that involves all players but at split starting locations.
This scenario relies primarily on the Round Limit to provide difficulty, featuring several level 1 Challenges of minor note. However, every little bit of damage may count; if a hurt PC is forced to take the Leap of Faith at the end and misses, that 4d6 resulting damage can easily result in an Injury. If you want to bump the risk levels further, swap the Ant Swarm for Cave Bats (and either add a nearby cave to the description or reflavor these to some other kind of dangerous creature) and the Noxious Fungi for Blue Mold or another Poisoned Surface. You could also add Fierce Winds to F if you think your players will reach the region in enough time to take the Difficult Road.
At lower player counts, consider dropping the Hidden value for the exit in B and/or reduce the EP of the Walls of Foliage a couple points.
Sometimes chase scenes are more exciting when, instead of a general round limit, there's an incrementing limit as the PCs advance. This can “feel” more like having a foe right behind you (as opposed to, say, trying to escape an area before it collapses). If you want to run this scenario that way, have the PCs start with a 2 round limit. Increase the round limit by 1 when all PCs have made it to B, again when all PCs have made it to C, a third time when all PCs have made it into D or E, and one final time once all PCs have made it to F. This method is also useful for ending a doomed scenario early if the PCs have bad luck at the beginning.