Sieges take time to get to you. You can avoid being wiped out in your first year by building farther away from other forts.
So what happens when the map is almost filled? Theoretically it'd happen eventually.
Or people troll and build close to you? Someone awesome at the game wipes their awesome fort, starts a new one right next to somebody else to try to zergrush them? What now? It'll happen. It's the internet. Trolls will come eventually.
Traps and walls are very clearly overpowered. To make the game more fun/challenging, both for online play and in offline, spear users should check the ground ahead of them as they walk giving them a 50% chance to set off and break any trap they come across.
Why not send in a bunch of Spearwielders to de-trap the zone every time?
Traps would be useless then. Spears would need to be broken to balance this.
Wooden walls can be torn down by axes, stone and metal walls can be torn down by hammerdwarves. Obviously metal walls would come down very slowly even with the best hammers.
Why would anyone ever build anything but metal walls? Of course stone at first, but eventually the entire fortress would be lined in metal. At least the entire entrance-way would be thoroughly and ridiculously lined with metal so that you'd never get through as long as their gates were closed.
And nobody would use wood if it was easy to take down like that. That and it'd be a waste of resources you could use for other things.
Then again the question becomes this: Do you mean
Defensive Walls or
Interior Walls? By all means the wall between 2 dwarf bedrooms is not going to be as thick and well-built as the wall between your fortress and your primary entrance... as a wall built for defensive purposes.
Walls built [properly] for defensive purposes? You aren't getting through with an axe or a hammer. That's the purpose of them. If you do, then there's nobody defending the fort. It'd take you so long to chip your way through you'd either be chased off or killed while trying. Assuming your weapon is of fine craftsmanship and holds up. If you do manage to succeed... then you should probably leave the newbie alone and let him know he needs some crossbows guarding his walls from being broken into.
This is why siege tactics were developed. Sieges weren't meant to be easy. Fortresses were built specifically to keep people out --
to really make it as hard as humanly (or dwarfenly) possible for anybody or anything to get inside once you close your gates. This is why rams, sapping & tunneling (I had a big series of posts on this elsewhere, as well -- sapping was difficult and ineffective - tunneling in was even more difficult and ineffective -- not to mention both were very dangerous), siege weapons (trebs, cats, etc.), siege towers & siege ladders, and other siege tactics were developed! Infiltrating and opening gates was a good tactic (sacrifice a few instead of taking amazing casualties and crippling your army trying to get in).
Assaulting a castle often took lots of balls. Far more attackers would tend to die than defenders. You try climbing a wall and having someone up top waiting to kill you. Sound fun?
Another common way to siege? Sitting the heck down and taking a load off. Just barricade a city/castle in, cut them off from supplies and trade, and let them rot and slowly die inside until they give up or die. You starve them out. If you're real lucky someone might get tired and lose their head, and opt to open a gate trying to get out/let you in so that an end could be put to this madness and the cruel, hungry, slow, diseased, disgusting death.
I also support the addition of far more in-depth siege warfare. Can you tell? ^^;
Though starving out would be boring, it's an effective method. Especially if you dig in real good. Then your enemy has to open the gates and attack YOU if he really wants you gone (and wants his dinner). Then he has to lose lots of troops forcing you out of your heavily defended mini-fort. Or... he could surrender. Though this wouldn't work too well in Dwarf Fort, seeing as you could just have underground farms to feed your population. Not unless some people were inexperienced or not dwarfen.
That's just one of the problems with trying to get Fort Mode working in a Multiplayer (or Massively Multiplayer) setting. Sieges aren't easy. They aren't fast. If they are, somebody is doing something wrong and you probably aren't the guy they would have put in charge of that sort of thing to begin with.
Right now you could just simply "dig" or "build ramp" or even "dig stairs" and "build stairs" to get in. There would have to be some fundamental change to keep these things from being done and forts becoming real easy to overcome. Otherwise, somebody would be inside your fort before you got your stuff together. You'd be slaughtered, you'd lose everything in a matter of moments. Nobody wants that crap.
Perhaps attackers would be locked on soldier status. If you wanted to dig through stone you'd need to bring Engineers. Basic defensive positions, channels, small wooden bridges, wooden barriers, etc. should be able to be built by the soldiers themselves so they don't need to be standing out in the middle of the open waiting to be slaughtered. Anything more advanced would require engineers. Building siege engines/weapons should be the job of Engineers as well. Ladders should be easy enough for a soldier to be able to figure out how to build.
Though if I may make a suggestion to everybody, do click the link in my signature. It has a few ideas for MMODF that could work out a little bit better than "MP Fort Mode".