Hi Weron! The evasion rules are very abstract, so I can understand why they are hard to narrate. Hopefully these answers to your questions will help.
- This appears to be totally independent of distance to the opponents. Is it not harder to flee if the enemy is 30 yards away than several hundred yards?
The first thing to keep in mind is that evasion does not necessarily mean "outrun". A character who hides has also evaded the enemy. The classic example of an ACKS evasion would be the scene in Fellowship of the Ring movie where the hobbits see the Ringwraith and duck into the hollow on the side of the road to avoid it.
The second thing to keep in mind is that the rules explicitly state, "The Judge may modify the probabilities based on the conditions and environment. For example, if one side has time to flee within a densely wooded area, the Judge may give a bonus of +5 to flee. If the party giving chase has double the movement of the fleeing side, they might receive a bonus of +5 to catch the fleeing party." So as Judge you absolutely may give a bonus or penalty as appropriate.
That said, if you reveiw the Wilderness Encounter Distance table, encounters at closer range typically occur in dense terrain with constricted line of sight. Compare Marsh (8d10 yards) with Plains (5d20x10 yards). An enemy encountered in the steppe at a range of 500 yards might be impossible to evade, while an an enemy encountered at 30 yards in a dense swamp might be easy to hide from.
So while it's true that Chance of Evasion should decrease as Encounter Range decreases, Encounter Range decreases with Terrain Density and Chance of Evasion should increases with Terrain Density. The net effect cancels out. That's why the table uses number of characters fleeing as the primary factor. It takes a bigger hiding spot to hide a large party!
- It is also independent of activity. Like, if one group is camped and the other is moving.
Again, the rules explicitly state, "The Judge may modify the probabilities based on the conditions and environment. For example, if one side has time to flee within a densely wooded area, the Judge may give a bonus of +5 to flee. If the party giving chase has double the movement of the fleeing side, they might receive a bonus of +5 to catch the fleeing party."
- Can you decide to flee when engaged in melee, by using the "retreat" initiative action?
Yes, although it would be complex. Everyone in the party would have to take the retreat action, and then succeed on a Wilderness Evasion throw. Until then, the combat would continue at a tactical level and distance would be measured by the Judge based on movement rates.
If the party wants to scatter, then each character who retreats could separately roll to evade, but they'd be off running in different directions and the Judge would be advised to use some sort of random factor (perhaps the Lost rules) to make it difficult for them to easil re-group, unless they've planned a rendezvous point in advance.
- If you have less movement than the opponent, what stops the opponent from just "running you down"?
As noted above, evasion isn't just about outrunning the opponent - it's also about outsmarting them through use of terrain. Genuine wilderness terrain can be dense, confusing, and disorienting to an extent that typical city-dwelling people cannot fathom - people often get lost and die very short distances from roads. It has impassable hills, fallen trees, hidden caves, crevices, etc.
So perhaps you found a short cut leaped over a chasm they didn't dare to cross. Perhaps you climbed up a tree and they ran past you. Perhaps they saw an animal trail and thought it was your trail. Perhaps you found a pass through a rugged hillside that they missed. Etc.
That said, this all assumes there's some measure of terrain to work with (and even plains have some). If you look at Chases at Sea, where line of sight is vast and terrain is non-existent, the evasion throw is based purely on the difference of speed. You could use that as a basis to extract modifiers based on the difference in speed where appropriate. (And even at sea, by using wind patterns, ocean currents, and shallow waters, it's sometimes possible for a slower ship to escape a faster ship, though obviously much less common.)
- If you have less than 12 constitution, will the monster catch you when you can no longer run but it can?
There are many places where Constitution arguably could be brought into play to affect mechanics, but in general ACKS like other OSR-inspired games does not heavily focus on ability scores. You certainly could, if you wanted, impose a penalty on the evasion roll based on the lowest CON in the party. But I think CON would more usefully come into play if the attempt to evade fails, and the enemy keeps the characters in sight, turning it into a day-long pursuit.
- Is all this just math? E.g. encounter distance - difference in running move and constitution?
Definitely not, for the reasons stated above.
The big one: Why are there even rolls if the chasing group is not faster than the fleeing party? The chasing group will never catch them. Note that this includes same speed groups.
What if the fleeing party runs into a dead-end, like a canyon that has no way out, or a murky impassable swamp, or a stream that can't be forded?
My players have learned to always call out "Evade" whenever a wilderness encounter occurs. They have an explorer, so a pretty good chance to succeed right away. I have almost given up on running wilderness encounters, as I have a hard time narrating what is going on with the evasion rolls.
Your players are wise to do so! That's what they SHOULD be doing. It's very hard to survive in the ACKS wilderness if you don't evade a lot. But, what tends to happen over time, is that parties tend to become bigger. Mercenaries, henchmen, and hirelings get added to the party; mounts and beasts of burden for capturing loot; merchants for goods. This tends to make it harder to evade and so encounters become more frequent. Put another way, the rules are designed to help small, low level parties flee easily while big bands cannot.
Here are therefore some default narrations to use that should help exemplify what's going on with the different situations:
Fleeing party faster and escapes: "With your great speed, it's not long until you've left the pursuer far behind. Soon it is out of sight, and you've escaped."
Fleeing party slower and escapes: "You could not hope to outrun the pursuer, but a [densely-foilaged tree with low-hanging branches]/[cave mouth hidden by brush]/[hollow in a fallen oak]/[old animal den] proves your salvation. The enemy loses sight of you, and you've escaped."
Fleeing party faster, fails to evade, and pursuer catches up: "Your speed comes to naught when you run into a [canyon with no exit]/[unfordable stream]/[cliff edge]/[impassably dense shrubbery]/[morass of bog]. Hemmed in by the terrain, you are caught and the fight resumes."
Fleeing party slower, fails to evade, and pursuer catches up: "The pursuer runs you down and the fight resumes."
Fleeing party faster, fails to evade, but pursuer doesn't catch up: "Perhaps had you chosen a different route, your speed might have allowed you to escape, but the [broken canyons]/[muddy morass]/[twisting trailways] you followed slowed you down. The pursuer must have known a better route - it remains on your tail."
Fleeing party slower, fails to evade, but pursuer catches up: "On even terrain you could not hope to outrun this pursuer. But you found a short cut that the pursuer did not, and the [broken canyons]/[muddy morass]/[twisting trailways] slowed them down enough to keep the chase going. The enemy remains on your tail."
4. If evasion failed, roll for catching up. 11+, +/- 2 per 25% move difference.
Great rule!
