Iden, how about about supply convoys ( war realism, ftw ) and the remaining trees act as obstacles ( physically, and visually... ) , and other ways for the AI to tempt fate, and resources, to get in.
Like Siege Towers, they like moving stairwells, or if they are tipped over, bridges, maybe ramps, if they land on a wall.
Rafts, boarding planks, or bridges ( if something big throws it ) .
Grappling hooks, biting harpoons with ropes ( personally large enough for a ballista ) , or rocks with ropes and a catapult.
Erm, large and meaty steeds that can launch themselves over broad moats, and/or high walls in one bound.
Maybe large flying steeds?
In another thread (I don't recall which one -- im too tired to recall or bother looking for it -- but it was about tunneling and siege) I posted a bunch of stuff, and a lot of interesting things came up.
Convoys would be great -- for long lasting sieges. Otherwise they're not really necessary, y'know? Disrupting enemy supply trains would be a fun way to help save your own butt. Right now Toady's working on more military stuff, and eventually it will be possible to worry about the really complex stuff like long sieges, supplies, troop movements.Eventually you should be able to build an army, build siege towers, siege weapons, ladders, rams, etc. and bring them with you, setting them up safely outside enemy territory and rolling them in while in formation.
However, i'm currently addressing the near-future. Right now we don't even have movement, we just have our own places under siege. This is just basic stuff to improve the game as-is, not taking into account possible changes. Though I would love to see the expansion into broader ideas, such as you suggest, in the future after more stuff has been implemented.
Trees in fact
should be obstacles for siege towers, engines, and weapons movement. You'd have to cut them down or move around them. Though, trees do not affect Line of Sight in Fort Mode. So unless that was to be changed, it doesn't make much a difference, really, other than being obstacles for movement.
Advanced techniques for siege would have to be assessed by Toady, though I do think some sort of grappling should be implemented. Mostly by elite squads of soldiers with amazingly high Ambush skill. They should be able to employ grappling hooks to use to scale walls. They should also use AI to attempt to pull levers near gates, in order to let their friends in. Though, of course, this could be overpowered, and would indeed be somewhat rare.
Somebody in one of the threads I refer to (one of these days i'll find it and link it to you guys -- just not right now -- there's a grand quote about what i'm about to mention) mentions how somewhere he recalls reading (possibly in one of Toady's bloats, about things he'd like to see possible) something about Elves mounting Flying Eagles and dropping down inside an above-ground fort, in order to stealth and ambush people. Personally I think that would be truly awesome - and I hands down want to see it happen. I just hope it's not easy to piss of the Elves enough to make them want to do it, is all.
Sieges:
Well if the fortress is aboveground, then it is quite likely that if they can find a quite corner where they don't get killed by bolts that they will merrily dig a tunnel under you walls.
In any circumstance really, if the enemy clearly isn't getting in via any visible entrances, then they will look for alternatives, probably just sit outside for a few years, killing anything that isn't protected by the fortress. Maybe pelt you with arrows on occasion. If the fortress doesn't seem to mind being cut off, which would probably be worse than it is now, then they will probably resort to tunnelling into the fort, which would take a while. If the fortress failed to dislodge the siege, and the siege fails to dislodge the fortress, then a tunneller breaching the fortress is basically inevitable...
First off, if there
is such a corner, the defenders are doing a poor job and deserve to fail. Secondly, you start digging from outside the firing range of archer fire and any siege weapons. You'll just be mauled with arrows and lose men if you start from inside. Not unless your plan was to distract the defenders and draw as many of them as possible to that spot so you can mount a flanking action and scale the walls somewhere else in hopes of getting up that side of the wall and securing it for yourself before reinforcements can get back to repel you.
Tunneling could be inevitable. But there should also be a chance of quitting the siege. After a couple of years, if no progress is made, eventually the attackers will get tired and give up (if they're not starving you out and theres no sign of it). The only advantage you have at this point is that you can get reinforcements while they likely can't. If no reinforcements can come to your aid, you're best of giving up as you'll lose more men than they will and be unable to recoup your losses in order to overcome them. If you have reinforcements, and don't mind losing the men, it can be an option. Though only a desperate one. Chances are if they're not goblins being led by demons, they probably don't care about killing you enough to waste that many lives needlessly.
What odds are acceptable for a fortress to be breached by a tunneling creature?
*blink blink* what?
What odds are acceptable? 23%
I think a bit of clarification is in order. In what way is this different from the 16 page discussion on tunnelers like...two threads away from this one?
Personally, if you ask me, the quantification of such a number can never be a correct representation of what it should actually be. No, i'll agree to a point it shouldn't be a larger number than any of the other options present at any given time. But given the variability of circumstances, fixing a value to such can simply never be correct. It should always be a variable -- one that is always less probable than any other option before the other options have been used and discarded from choice. It also should be a variable, at times, that should be impossible (0%). It should also never be 100%. It should never, and can never be the only option. Worse comes to worse, there are always
at least3 options whenever digging may be considered: Quit the Siege, Wait out the siege (attempt to starve them out), Dig.
This does not make it 33%. Different circumstances may altar values. Digging needs digging tools -- no digging tools, no chance. Is there enough food, or supplies coming soon, in order to feed your men while they wait out the siege? Easily if there are no supplies coming, and supplies are low, waiting out becomes a lower % (probably 0%), and the other two would inherently increase %. It would be between digging and quitting, more likely than not. This also doesn't make it 50%. There are other factors, including some random factors, that would modify any numbers. So at any given time it could be any number. But weighing all options before have been tried, digging should never be considered a majority at any time.
So 23% would probably be a bit high of a number, when the siege is started. Other things should always be tried first. Though over time, the army might get desperate and be more likely to try to dig, or they might just give up.
Edit: Sorry for the unadultered bold earlier. I had a major headache, it eluded me. Just getting to fix it now. ^^;