Deathworks;
First let me say thanks for being a consistently positive poster on these boards. I'll go on to agree and list off my points... I'm on my 8th year in a 3104 fortress and while I initially hated DF31 due to the spacebar\esc change, now that I've successfully worked around that problem it has allowed me to see a ton of love has made its way around the game.
* Injuries \ medical care \ the hospital provide an interesting area for activity in the fortress. My hospital is a big diamond-shaped square with diagonal doorways leading in and the walls are lined with traction benches, tables, and beds. The center of the floor is a massive clot of bags and boxes filled with medical junk. Dwarves zealously rush here with newly-produced cloth and plaster now and then. When someone is injured they tend to get a lot of attention: a separate dwarf comes to diagnose, treat, feed, and water each dwarf and someone even comes to wash him. I haven't seen anyone giving an injured dwarf any booze, but I read that it happens...
* The underground is a hell of a lot of fun so far. I've only worked extensively on the uppermost layer, the mostly-dry mushroom forest. It has numerous map exits both wet and dry and creatures large and small spawn and roam through the map. The fungus in the richly fertile mud grows like a virus and requires year-round chopping to prevent its choking off of critical pathways, and the ground-cover plants provide more than enough food for 34 dwarves. As the years roll on, with a bevy of grates and bridges and staircases and ramps, miners work ardently to claim the precious treasures of the underworld from its reaches. Naked mole dogs scurry about now and then, ignored by my dwarves as non-threatening. The military sweeps through with a flurry of steel axes and sends their limbs flying into adjecent caverns and permanently (!) decorating the immediate cavern with their blood.
Several times a year, drawn by the incessant thumping and scratching and scraping of the dwarves' work, the old ones come... The beasts forgotten to creation, too ugly or evil or awkward to make a living in the surface world. Some fell to the flashing axe, but others were stronger... crafted of materials strong enough to forsake the mortality of flesh. Fearing no enemy, the dwarves turned the fury of the stone itself against these monsters and left them broken among the debris. Fearing ambush by the ilk of these beasts, the dwarves sealed off nearly every water and land route out of the county, from floor to ceiling, with walls of lustrous dolomite. When the beasts come and rap at the walls, we lay an ambush of rock and stone and pillars that none can survive.
Seeing just a few new doable things here and there really livens the game. I can make traction benches at my mechanic's workshop. The alchemist is gone and replaced by the soap-maker's. I modded in a Foundry workshop: you can take a stone mechanism, 1 unit of gypsum, and 3 units of nickel, iron, or steel to create a metal mechanism using reverse mold casting. The stone mechanism is consumed but that hasn't bothered me so far.
What I would love is if I could have the input quality of the stone mechanism result in equal quality for the metal mechanism: i.e., you are literally casting exact metal copies of the stone mechanism. For now, the metal mechanism is always base-quality.