- If you designate stockpiles underground,
construct a floor under them, it stops items from decaying. If you don't construct a floor or cover the dirt/ground, but instead, just have them sitting on grass/clay, everything degrades at a very rapid rate, regardless of the material it's made of. Constructed floors can be made of limestone, wood, twigs, or clay bricks.
- What your settlers have for skills matters, but some skills don't matter in the slightest. Botany, Mining and Smithing are probably the most important to have at least 2-3 Settlers with a skill of 20+ when starting.
- If you choose to participate in the Research tree (instead of simply granting them) you'll also need at least one with a high enough Intellectual rating to produce books that you allocate to gain parts of the tree. If those books decay, you have to replace them before you can advance in any new Research. You don't lose the skills, but you can't gain any more. It's vital, then, that books be stored on a constructed floor.
- Traps work. Especially the metal floor traps. I've had one of those take an invader down to 10% health, and then a spike trap finish them off. Huzzah! Trap Hallways!
- You can lock doors and have trapped long alternate entrance hallways to guide your invaders.
- You can create murder holes with archers. I haven't tested it with grated doors and windows yet, but otherwise, it does work in general.
- Metals progress from iron to steel. There is gold, but I haven't found any, yet. Steel requires iron and coal, you can make coal in a kiln.
- Trees are infinitely renewable. You can simply plant more and cover the entire above ground map in new trees after you raze it, if desired. Of course they take time to grow, but it's not unreasonable. The wood and sticks are your fuel sources for everything, so you really need to attend to this.
- Food production is extremely important when starting out. You need to suck it up and plant a cabbage field, and likely one field of each type of crop you can, as soon as you start. Do not delay, or your settlers will starve.
- Because I didn't know about the constructed floor halting decay, my first play through was essentially running a pitched battle in the face of all armor, weapons, clothing, everything, rotting away before my eyes, within a single season, in some cases. It's that important. But, once you have a place to store food that doesn't spoil as quickly, it makes all the difference in the world. For myself, I ended up focusing on pickling/preserving (which you can do with vinegar or salt) because everything else rotted. That wasn't necessary, but it is an interesting mechanic, because salt is non-renewable, but vinegar you can make indefinitely, provided you have anything fermentable (any plant), and fuel (wood/sticks/coal).
- While digging underground, you have to brace the walls every so often. I can say with certainty that you can dig out a 7x3 area, and then place a single wooden beam across the entire 7 span at the far end, then continue digging another 7x3 area, adjacent (on the long edge) and continue that indefinitely without cave ins. Larger than that, and You'll see the middle fall away as unsupported. I don't know the exact limits, but 7x3 is what I calculated based on early failures.
- different weapons, shields, and armor have different perks, some attack faster, some grab shields, all do the job fairly well. I went with one handed swords and bucklers, and have survived the first year and 5 different raids in that time.
- Crafting weapons is relatively fast. Crafting armor, especially metal armor like Mail (chain mail) is extremely time consuming. A single piece of mail armor (body covering) takes more than a full 24 hour day of effort of one 20+ sill smith. It's a big deal. I have no idea about plate yet, haven't achieved that yet.
- Raids come at least once per season, and a season lasts 12 days. As has been mentioned, cold is no joke, and you want to make sure everyone has Winter clothing. Again, store it in a stockpile with a constructed floor, or it will rot away into nothing before winter arrives.
- Raids are just a type of event, and there are several different event types. So far I've seen starving refugee, escaped slave, hostile animals, hail storm, thunderstorm, and straight up bandit attack. Often, the settlement is given the choice to accept a new citizen (you see what they have to offer first) before you make your decision, and if you take in slaves or criminals, their hosts/owners WILL come for them. You're given warning of how long before they arrive, though, so you can prepare. In some cases, it's just slightly longer than a day, though, so if you don't have the armor and weapons already, too bad for you.
- Handling the cold underground is really elegant. You build braziers (out of a large range of materials) that each produce enough heat to heat a reasonable sized room. However, in the sleeping area, which currently has 9 beds in my starting fort, I put two braziers in, to keep the temperature above 20'C all the time. On the other hand, I left the storage room without any braziers, and all the harvested crops do not rot, at all, in that room. It's literally a cold storage room, regardless of the season. The temperature was about 4'C even on the hottest summer day. Normally at or below 0/freezing.
- There is hunting to obtain leather, and you can make clothing (summer/winter), caps, and basic armor out of leather. Cloth comes from growing Flax, which produces linen on harvest, and can be used to make summer/winter clothing, but not armor. It is required in making 'packaged food' though, which is apparently better in some way. I have pursued the farmer/gathering path, rather than the hunter/butchering path. They're not mutually exclusive, I just haven't tried Hunting yet. The consequence of this is that I went from cloth->metal and skipped leather entirely.
- Food can be eaten raw or cooked. Negative thoughts from Raw food, good thoughts from cooked food/meals. There are Lavish meals. The simplest form of food generation is just a campfire, and any raw food you can gather or grow (mushrooms, currants, cabbage, carrots, all that) which then produces stew. However, here again, you need to store it on a constructed floor, or it rots quickly. Raw food has 30 nutrition. Stew has 95.
- Production of anything has fixed amounts, make-it-forever, as well as make-to-a-limit set points. So you can say, make stew, but stop when you have 10. It will auto-restart at any value under 10. Very simple and effective. Each production station (from campfire, to kiln to armoring table, smithing table) has fields to edit for fuel sources as well as input items. You can, for example, using sticks purely as fuel, to avoid consuming wood unexpectedly.
- If you plant a field of redcurrant shrubs, they will automatically be harvested once they reach max yield maturity. Not so with birch trees, but shrubs work as expected. Trees you still have to manually designate to be chopped down.
- There are at least three types of alcohol, 2 of which require Barley, so that's a long term crop if you want to supply Ale and Beer. You can provide wine pretty easily though from Redcurrants. Brewing stations produce vinegar, wine, and the other items, once you have Fermentation granted or researched.
My current entirely underground fort: (sorry for the blue tint/snowing, it's wintertime)