Dwarf Fortress started development in 2001, and no public release was made until 2006.
Originally the game was simply 2D (meaning, there were no z levels. You could not go up or down). There was no variety in the maps. On the left, there is a grassland, and on the right side, there is a mountain, further in a cave river, chasm, magma and then adamantine/the Pits.
Then, the 3D version was released, with the major addition of Z levels, and mechanics. This expanded gameplay tremendously, but made underground rivers, magma, and creatures etc unique to their landscape. To clarify, this is not in a 3D view, but adds 3D features. Whereas in the 2D version you could go left and right, x and y axis, the 3D version adds up/down, the z-axis. Once more, THIS IS FROM THE SAME VIEW AS THE 2D VERSION, TOP-DOWN.
Released on April Fools Day 2010, DF 2010, the latest big update, was an overhaul to a huge chunk of the game, that took over a year to do! For example, Combat has been changed, materials and items reworked, Dwarven Healthcare introduced, Burrows created and the Underground overhauled, to name a few! Take a look in the new version subsection of the Features section for a more detailed changelog of what's been added/changed!
The latest 2D version is here
Note: The 2D version is no longer updated and lacks many of the features you may be used to in the 3D version, though it's still a lot of fun.
The latest 3D version is here:
Military Use in DF2010:
Before you can do ANYTHING with your military, you need to designate a militia commander in the noble screen (n). Don't worry, he doesn't have any requirements and doesn't set mandates. While you're at it, designate an arsenal dwarf too, and give him an office somewhere - he's the fortress quartermaster, and without him your squads won't end up with any equipment other than what they were already wearing.
The way it works now is that every squad leader is designated in the noble screen - once you designate a militia commander it will open up a slot for "Militia captain", and once you designate one of those it opens another captain slot, etc. As far as I can tell, these roles are all functionally equivalent.
Once you've designated a commander/captain, going to the military screen (m) will show that dwarf under the "Squads/Leaders" heading and you'll notice an option to create a new squad. Doing that changes the the display of the dwarf from his name to the squad's name. You can then fill out the squad from anyone in the fort by filling in the "Squad Positions" heading.
Okay, here's where people seem to start getting lost: Equipping your squad. The first thing you should look at is the "Uniforms" tab. You don't actually need to change anything here, but it's good to understand how just in case you want to. Each option under the "Uniforms" heading is essentially a pre-designed set of equipment that you can quickly apply to any individual soldier or entire squad. You can create new uniforms if you want and add or remove items from any uniform by navigating this menu.
Now go over to the "Equip" tab. Here's where you can apply those uniforms to individuals or squads. You can also straight edit a dwarf's equipment from this screen - if you want to give someone an artifact for instance, you can just select him, go over to his equipment list, get rid of whatever the normal uniform option is for that slot, and hit the hotkey listed at the top for whatever type of item the artifact is - if you select "Specific X" it will give you another list of all the items of that type in the fort (I believe it sorts by highest quality at the top, so you don't need to hunt around for the best stuff). If your squad is using ranged weapons, head over to the "Ammunition" tab and assign them something from there (If you don't care what they use, you still need to give them ammo - just pick "Bolts" and it will default to any bolts they can find).
If you've got an arsenal dwarf with an office, your squad should now retrieve their assigned equipment as soon as the arsenal dwarf signs off on it (Assuming they can find any that meet the types you set).
Getting your Squad to do Something
Here's another big stumbling block a lot of people are having - training. It's not quite so simple as just designating a barracks and letting your dwarves have at it anymore - though once you know what to do it's not that complicated, and it gives you a LOT more control over military behaviour than before.
First thing you should do is designate a barracks somewhere, the same way you would have in the previous version (Though you can also designate barracks from a lot of other object types than beds now - any storage object can also be used to designate a barracks or armoury room).
Once you've designated a barracks, you'll notice a list of the squads in your fort in the info pane. This is where you set how the squad uses the barracks - it defaults to empty so if you don't do anything here, your squad won't even know the barracks exists. You probably want to at least enable "Train" and "Sleep", though really what you set here is up to you, it's more important that you know it exists. If you don't have the squad set to "Train" at any of your designated barracks, they won't train. There are also options for storing equipment here - I haven't seen my dwarves doing this but I've got them all set to just leave their stuff on even off-duty, so I imagine it's more meaningful if they switch to civvies. There's also a "Position" option where you can assign specific beds/storage to specific dwarves. I don't think this is too important unless you REALLY want a particular dwarf to have the NICE armour rack. If they aren't assigned they'll just use whatever they feel like, as normal.
Now, just designating the barracks won't get them to train - because they're still off-duty. Head back to the military screen and go to the "Alerts" tab. This is sort of like the uniform tab in that it's a way to quickly assign specific behaviours to a squad - though unlike the uniform tab you really HAVE to use this one. All squads default to inactive until you set them to an alert level - you can create your own custom alerts but to keep it simple for now, just set a squad to "Active/Training". Note that to set a squad alert level, first you scroll down to the alert, then you scroll across to the squad, THEN you hit enter. If you just hit enter on the alert itself, it will set the civilians in the fort to this - for "Active/Training" it's essentially meaningless, but you can use this to order civilians to a safe area in the event of an attack (Kind of like the old "Keep indoors" option, but much better since they don't keep trying to run out the front door and turning around).
Once you've set the squad's alert level, head over to the "Schedule" tab. Along the top you'll have a list of all the squads in your fort, and on the side will be a list of the game months. Now, this is important, on the VERY top of the screen, above the squad list, is the name of the currently selected alert level. You can change this with the */ buttons on the numpad - what you're doing here is setting the squad's orders for each month when they're set to the selected alert level. If you're on "Active/Training", every month probably says "Train".
Here's the thing - the game defaults to a REALLY stupid option that most people are probably going to miss - notice on the bottom, in blue, how it says "Train, 10 minimum"? What that means is that if you have less 10 dwarves in that squad set to training (Which will always be the case since squads max out at 10), it will FORCE members of the squad to train, even when they're exhausted or starving. If you don't change this, your dwarves will be EXTREMELY miserable after a while - they might even starve to death while training - I'm not sure. Either way, hit "e" to edit the order, and use the /*-+ buttons to set the minimum to something like 1 or 2 less than the number of dwarves you have in your squad.
If you hit "o" while on this screen, you can scroll through all the other options for orders you can give your squads. All of them except for Train will require you to set either burrows or notes while I'll explain in the next section. For now just leave it on train.
Don't forget that orders are set per month - so you only set the minimum down for one month. Copy/paste the order into all the other months. Alternatively, if you want to give your dwarves time off, you can just hit x on an order and it will set them to inactive for that month. You can also use "o" to give them more than one order during a given month, though I'm not sure how this works (My guess is that if you set your minimums properly, the squad will split evenly between the two activities to maintain the minimum values of both).
If you've set everything I mentioned above, your dwarves SHOULD spend some time training in the barracks now. Bear in mind this is a new release and pretty buggy, and dwarves weren't exactly rocket scientists in the last version either, so it might seem like they spend a lot of time waiting around for an instructor or instructee. If you just leave them alone and don't worry about it, eventually they'll figure it out and start getting some training done.
Burrows and Notes
This is a more advanced feature of the new military options - it's similar to the old station and patrol options, but a lot more flexible because of the new alert level settings.
First things first - if you want your dwarves to guard an area, you need to set a burrow. It's pretty self-explanatory how to do that once you hit "w" from the main menu - just cover the area you want the dwarves to defend. Note that bigger is better here, at least if you want your dwarves to cover a wide area. Dwarves will detect intrusions into a burrow, and if they're set to guard that burrow, they'll immediately run to the point of the intrusion - so don't set the burrow to one square to try to get the dwarves to stand at the entrance or something. Just set it to the area you want guarded.
Burrows have a few other uses as well - you can assign civilians to burrows and what that means is that they'll only use things that are in that burrow - workshops, dining rooms, etc. Note that they'll still gather material from outside the burrow if it's not close at hand, so don't worry about dwarves starving in a burrow because there's no food in it.
Notes are how you set a patrol route. This is a bit more complicated than it used to be, but essentially, first you have to plant notes at all the points you want the dwarves to patrol, then you need to hit "r" from the note menu to bring up the routes list, and create a new patrol route and then add waypoints to it. It might seem excessively cumbersome, but the reason behind this is that you can use the same points for multiple patrol routes, if you want different squads to follow different paths.
For either of these, once you've set up the burrow/route, you can set a squad to use them via the "Schedule" screen, the same way you edit their training schedule. You can also set dwarves to just stand at a particular note like the old station option, but honestly using burrows sounds better to me. A good idea is probably to create a new alert level for "Active" duty versus just training, so you can quickly have switch your dwarves between patrolling and training.
There's also a "Burrows" header on the alerts tab of the military menu. To be honest, I don't actually know what this does. My guess is it's used to send civilians to certain burrows if you set the civilian alert level to a burrow restricted alert.
This is probably the simplest thing to figure out of all the new options, but I figure I might as well be thorough. First thing is open the squad menu with "s" and select a squad with a,b,c etc. (You can also select multiple squads by holding down shift and selecting a squad). Honestly, from here it's pretty intuitive. Just hit the appropriate button for the order you want to give, pick a target, and watch them go.
You can also give orders to individual members of squads by toggling from "Select squads" to "Select individuals" with p, then selecting a squad and picking someone/multiple people from inside it.
I'm pretty sure that covers most of the basics. There's probably more advanced stuff I haven't gotten the chance to see yet, but that should at least get people far enough to have a squad training or patrolling the fort. If you guys think this looks good, I'll probably post it to the DF wiki.
The most stunning feature of Dwarf Fortress is that it creates a randomly generated, persistent world for you to play in. (The world is only "on" when you are actually playing in it, however.) When you die in either the adventure or fortress modes, your next game will be in the same world, albeit a few days later. You can visit your old fortress, or get revenge on the monster that killed your adventurer. If your fortress or your adventurer had done anything of particular note, there's a chance that the game will generate a legend for them, which you can read about in the legends section. (Provided you've discovered enough information about the legend)
* The world is randomly generated with distinct civilizations spanning over 1000 years of history, dozens of towns, hundreds of caves and regions with various wildlife.
* The world persists as long as you like, over many games, recording historical events and tracking changes.
* Command your dwarves as they search for wealth in the mountain.
* Craft treasures and furniture from many materials and improve these objects with precious metals, jewels and more.
* Defend yourself against attacks from hostile civilizations, the wilderness and the depths.
* Support the nobility as they make demands of your populace.
* Keep your dwarves happy and read their thoughts as they work and relax.
* Z coordinate allows you to dig out fortresses with multiple levels. Build towers or conquer the depths.
* Build floodgates to divert water for farming or to drown your adversaries.
* Much much more...
* Play an adventurer and explore, quest for glory or seek vengeance.
* Meet adversaries from previous games.
* Recruit people in towns to come with you on your journey.
* Explore without cumbersome plot restrictions.
* Seamlessly wander the world -- 197376 x 197376 squares total -- or travel more rapidly on the region map.
* Accept quests from the town and civilization leaders.
* Retire and meet your old characters. Bring them along on an adventure with a new character or reactivate them and play directly.
* Z coordinate allows you to move seamlessly between dungeon levels and scale structures fighting adversaries above and below.
* The combat model uses skills, body parts, wrestling, charging and dodging between squares, bleeding, pain, nausea, and much more.
* A dynamic weather model tracks wind, humidity and air masses to create fronts, clouds, rain storms and blizzards.
* Over two hundred rock and mineral types are incorporated into the world, placed in their proper geological environments.
* Add new creatures, weapons, plants, metals and other objects via modifiable text files.
* Extended ASCII character set rendered in 16 colors (including black) as well as 8 background colors (including black).