I've been following the game for a couple years and I'm a big fan. It has developed quite a cult following and the author is living off donations (that's right, DONATIONS) from his fans so he can continue to work on the game full-time. Can you imagine yourself inspiring enough people in the world to send you $ for something you give away freely? Not many can do that.
The game has a high learning curve, the keyboard interface takes a lot of getting used to and of course the graphics are not the greatest. Vanilla version has ASCII characters (just as a Rogue-like has had before it) but there are modded tilesets that people have made which work fine for most people who need that. But how good can graphics get with a 80x25 tiled playing field? Let's be realistic!
The game's premise is it sticks you in a persistent world where your autonomous dwarves will end up making stories for you to be a part of and experience. Google "Boatmurdered" and you'll see an example of how this works. You basically
suggest actions for them to complete, like build a wall, dig a ditch, mine some ore, make a sword, etc. if they are sad or upset they won't really do much for you so part of the challenge is to keep them happy with nice living quarters, a good dining hall, and plenty of booze. Throw in the occasional event such as breaking into a demon pit, being seiged when you're not ready, or an arrival of a "mega-beast" such as a giant or a dragon who has already killed dozens of entities in the world and lived to boast about it, and you can imagine the types of problems you need to solve.
But the game is also a fantasy sand box, and if you are creative enough you can make your own fun. Spend 10 years having your dwarves build a giant tower made of Obsidian blocks and sacrifice goblin prisoners by dropping them off the top of it. Pump magma up into a giant stone bowl and flush it down a dry riverbed, melting a human seige force. The engineering components such as levers and switchplates are far enough along in functionality that clever people have made digital number displays and even binary adding machines. All powered by windmills and dozens of switches and levers.
You spend time solving problems like "how do I channel the water from the river underground to build a well, so my hurt dwarves can get a drink?". This might sound easy until you mess up something and it floods your entire fortress. To make a sword you have to mine out the ore, smelt it into a bar of metal, then make a sword out of it. Same with all the armor. To make food you must grow (or kill) it and process it somehow (clean/cook). Want an army of crossbow-dwarves? You must build archery targets and draft some dwarves into service (after you've cut down trees to make cross-bows and practice bolts with the wood). I won't even go into all the steps you need to take to make soap!
Of course I would play the older more stable version known as "40d" if I was to start out with it. This new version, after a year of adding things, is very buggy and it might get even more frustrating than it normally would. Once the major bugs are out it sounds like a lot better version.
The game is really exceptional and something
you can't find anywhere else. For those who get hung up on the graphics and the interface, it is really their loss. But they can always go back to playing Dragon Age or the next fancy 3D RPG/RTS/Sims game, right?

A 3D marble platformer using Newton physics.