Frame rate. The very steep CPU requirements are the reason I quit playing DF about, oh 5 weeks or so after I first found it. I found the Dwarfwiki and was quite happy reading through it and figuring out how to do things. Then, what I found was, I'd setup and grow a "successful" fortress, and it becomes unplayable.
So I started reading and searching for DF optimizations with a vengence; turn this off, turn that off, reduce Z levels, eliminate water. That last was particularly annoying; the engineering features seem quite fun, and I really enjoyed figuring out how to build a successful water system that pulled from an underground river ~12 Z below ground, pumping it into my trial and error water tower, then over a long constructed 'pipe' to pass over my wall and empty into my moat.
Then I realized my two days of work had been like shooting myself in the head, because now the fortress I was happy with before, was now unplayable because frames had dropped to about 4. Perhaps flow calculations should only be done when something's changed about the flow channel (i.e., it calcs the pumps pulling the water up into the tower, down the drain channel, and falling into the moat; and 'locks in' that as a simple routine that just knows where the water comes from and where it's going. And it would only recalc if I dig or construct or deconstruct to alter the physical areas.)
Along the same lines, after I figured out how to build a successful fortress that attracts immigrants, I realized that too was the same as firing the loaded gun into my left temple; past about 60 dwarves, frames drop dramatically. 'Play' became loading a text file on my second screen and reading, looking over every ~15mins to take a few clicks at this or that, then returning to reading while I waited for DF to chug along for, literally, another couple of days.
I was willing, grudgingly, to forgo engineering projects if I was allowed to play the game otherwise. But I couldn't see how to build a fun fort that worked well with less than at least 70 or 80 dwarves. And that's more than my computer can apparently handle. This from a computer that can run GTA4 (which is also a huge pile of unoptimization; I name it in this instance because it has an IMMENSE physics calculation engine in it, all running off the CPU, to calc the game world, the cars, and all the humans based on physics not preset animation loops).
The single thing DF needs more than anything else is code optimization. Sorry if this is 'uncool' or 'unfun' as a suggestion, but that's really the huge stumbling block. I spent about a month after I quit playing DF checking the Pathfinding thread daily hoping someone had figured out how to streamline the CPU requirements and give those of us not blessed with an overabundance of cycles the ability to play DF again; so far I haven't seen any hope. Now I check the thread every week or two. This thread gives me a small amount of hope DF might take a turn for the better.
I know it's not just me. Several of the popular "story forts" in the succession fort forum show the same complaints from successful forts. People were mentioning it in most of their posts; either they'd back out when their turn came up because they'd load the fort and realize it was going to take a month to generate a season, or they'd say "sorry I haven't updated my turn yet, game's still running". From my reading, the only complaint these folks had, in and around the TONS of fun they were having playing and handing the fort off to each other, was the CPU limitation.
Some programming excellence needs to go into streamlining how the code goes about the tasks. When I check the DevLog, I just sigh and despair, because all I see are yet MORE features being inserted I know are going to consume even more cycles.
Perhaps a user tool could be added to let us setup paths; I think most DFers use the concept of main hallways with directly connecting rooms. Such a play tool would require/allow the user to paint the main path(s), then connect from those to the required dwarf stops (food stockpile, bedroom block, water source, etc...). At worst, the pathfinding calcs could then be reduced to a dwarf simply having to make it to the nearest main path; and from there the calcs basically stop as (s)he follows the user set guide.
Please 3T! Take a month or two and apply your excellent programing skills to tightening and speeding your code! Please. Think of the unplayed dwarves suffering in virtual limbo hard drives the world over.
Assuming the game's playable, the biggest quirk I found was the incredible difficulty in having *any* sort of control over materials used for constructions. Trying to place entry bridges and traps was like attempting to buy the world a Coke(tm) all because the dwarves seem almost completely unable to simply move rocks that are in the way. The lack of a simple setting in the workshops to tell them "no, I want you to build Granite (x)". I found I was spending most of my dwarves' time having them clear rooms and hallways of unwanted materials, carrying them to far corners of the map, just to prevent masons and crafters from using the crap when what I wanted them was to use the nice, pretty, or valuable rocks.
World construction problems; namely, finding the needed features that allow a fort to actually survive. Water being a pretty big one, especially when any sort of river made the site unplayable. Also, Wood. Maybe this was related to my CPU limitations (using 2x2 or 3x3 areas), but I never found enough wood to have any hope of an actual metal industry without the use of magma. Then, still without industrially useful amounts of wood, I figured out I needed a site that was small (for frames), with an underground pool (for frames and survival), magma (for the fun of industry), AND with coal-like rocks. I think it took me almost a day of world gens to find a 2x2 site that met those criteria. !!!
!!!
Nobles and moods. I turned the later off almost immediately, when I realised they were randomly picking the requirements. It wasn't a challenge to obtain something I hadn't gotten to yet; it was a dice game where I might, or might not, have the items needed. So I turned them off. Nobles, almost the same thing. Their demands have no basis in what the fort can actually obtain. (Yes oh Duke, I know you greatly desire Platinum tables and Granite chairs; however, as it has been for the past 15 months, we still lack both Platinum and Granite, and the caravans do not bring them to us). And the noble penalties were the death of dwarves! My CPU limitations prevented me from building the engineering death systems many others seem to use to kill off nobles; but I did figure out that simply not naming a Sheriff prevented the killing of poor dwarves whose sole offenses were the inability to conjure materials out of thin air.
Dwarf economy; I ruined one fort with that and had to start over, when everything I'd been happy building became unavailable because all of my gainfully employed dwarves were priced out of the bedroom market. Entirely. I feel the economy, if it's implemented, should be a luxury layer, not a requirements layer. It seemed silly; the COOKS and BREWERS, who were the ones *making* the stuff, were unable to buy good food or drink! So where were the prices dwarves were supposed to pay for expensive food and drink going if not at least partly into the makers' hands?
I feel DF is one of the top ten best ideas in the history of gaming. For it to actually to become one of the top ten games, it needs to be polished and optimized. At that point, it'll easily rank up amidst Civilization, Mule, SimCity, Master of Magic, etc..