So, still playing through Avernum 6. Had some interesting experiences lately, both of which involved having to make a run for it, and not just because I'd challenged something stupidly big but because the plot was actually set up to make this a specific need.
In one situation, you're in an area that's going to blow up, but while you're trying to reach the exit, baddies who clearly lack any sense of self-preservation keep getting in your way. So you have to fight them, but you have to fight them fast, and if you want to loot them or any location you pass on the way, you'd better do it on your feet.
I've seen countdowns in "bigger" games, but usually the level stays the same throughout the countdown, other than perhaps some camera jittering, alarm sounds, and flashy lights. With this particular collapse, bits of the cave collapse in sequence, so rooms a little ways behind you are consistently blowing up and you can see that on the map. You know the countdown is real and that you are going to get BOOMed if you don't get out of here, it's not just some scripted event that will wait for you to get out so it can show a pretty cutscene of you leaping away from the explosion.
However, it wasn't actually difficult, at least at the level I had my characters at; there was plenty of time.
A trickier running battle involved a mission deep in enemy territory with no fallback points. When you get to your mission goal, you trigger a huge swarm of enemies to come after you (possibly infinite, I don't know). Also, you've just completed a huge mission so you may well be very low on supplies. There is a way out of this - you have to run a certain distance to a teleporter. But the enemies are coming from all sides, and if you stop to fight you may very well get overwhelmed.
My successful run involved sending my mage to go play "YOU SHALL NOT PASS" over a bridge to distract a large number of enemies so that the rest of the party would only be attacked from one side. This wasn't entirely intentional; a pathfinding quirk sent my mage off in a different direction from the rest of the party, but once she was there it seemed like the thing to do. The others still hit opposition, but since there weren't THAT many of them, were able to punch a hole through so that the fighter could leap for the teleporter, and once one person touches it, the whole party is outta here, even though the mage is now very 'dead' AND very far away from the rest of the group.
I suppose there's some logic to it when you're using a teleporter; since clearly only one person has to activate it to bring the party along, one party member being in a slightly different location shouldn't prevent them from dragging her body back for revival. It makes a bit less sense in cases where you similarly sacrificed one party member in a cave to hold back the approaching hordes while the rest ran for the exit with no teleportation involved; we clearly DIDN'T drag our friend's body back to town to be revived, but s/he'll wake up fine there anyway. (It wouldn't seem entirely unreasonable to me to make you have to pay some kind of retrieval fee in cases where you OBVIOUSLY abandoned somebody, so that it's still a viable strategy but one you can feel a bit bad about, but then, greater simulation doesn't always equal greater fun.)