Well, if you look at the development plans, Toady has a bigger picture plan for this. Not by increasing the difficulty of Dwarf mode to make it more Nethack-like, but by making an even bigger picture, so it moves from SimDwarf to something more like SimDwarf + Dwarf Civilization, with wars with enemy factions and things like that. To get a feel for that, look at the following:
CARAVAN ARC: As a prelude to armies, we'll have caravans actually move around the world map rather than just appear at your outpost. They'll move between each city on the map, though we'll try to stay away from supporting a real economy for the time being. You should be able to find items you traded in your fortress in adventure mode, and a caravan could come to your fortress with an adventure mode item. Related to Core3, Req204.
COUNTY ARC: When you get a baron, you'll be able to send out patrols. Once you get a count, you'll get a village outside your fortress and be able to organize armies. This arc would have to be developed along with the army arc. Related to Core27, Core28, Core29.
ARMY ARC: You should be able to control patrols and then armies in dwarf mode. The adventurer should be able to both go with and command armies. In dwarf mode, you should have the option to control your individual patrol members as you would in adventure mode. This comes back to adventure mode in terms of being able to control each member in a party of adventurers you make yourself. You could lead one and the others follow (as it is currently) or control them all, particularly during tense situations where you don't want to count on the AI. Entities should war with each other from bandit and monster raids to full fledged wars. Upset enties could patrol near their sites, leading to new wilderness encounters etc. Related to Core24, Core25, Core26, Core30, Core33, Core35, Req221.
NEMESIS ARC: The civilization leaders should be fleshed out in many ways. Related to Core11, Core40, Bloat68.
DIPLOMACY ARC: There should be a lot more diplomacy between your outpost and the outside world, especially as you get more nobles. Right now there's hardly anything.
and some of the longer-term stuff:
# HIGH LEVEL PLOTS AND DIPLOMACY: Various intrigue and interesting not-necessarily-violent conflict between entities and individuals. Once you place the actors in place, they should act according to their wants and the wants of their associated entities based on the strength of those ties. Both adventurers and dwarf fortresses can become immersed in the push and pull which arises from the AI. This is already true to some extent (the current quests are all created from the surroundings and entity ties), but these effects can be made pervasive. Since armies and invasions will be done before we get here, there will already be some of this AI in place to work with.
# LATE GAME: As you kill the large creatures, the world becomes more... boring. The game can be prepared for this kind of change and move over into a sort of fairy-tale/Beowulf/Robert E Howard type of hybrid with human civs and occasional monsters so that things continue to be interesting. This already happens naturally in a way, but the dialogue and reactions of people to these changes should be there to fully adjust to the new setting. Related to Bloat149
So, looking at that, it seems to me that Toady's plan isn't to make the current Fortress mode more difficult, per se, but to make it only a piece of what the larger game is about.
And if you think the current sieges are a piece of cake, you can bet that a war with an advanced civilization will be a bit more difficult. I'm sure he can code it to where, once an enemy civilization sees your fancy steam channel or weapon traps once or twice, they can find a way to get around it the next year, and then your standing army better be prepared.
[ November 14, 2006: Message edited by: Darkfall ]