Brendan of Untimately has a bunch of good questions.
- Ability scores generation method?
3d6 in order, but you get to roll multiple sets. Details here.
- How are death and dying handled?
Using slightly tweaked ACKS Mortal Wounds rules.
- What about raising the dead?
If you belong to the church of the cleric that’s raising you: 500gp. If you’re a stranger it’ll cost more. If your reputation is shitty enough, a whole lot more — or they might just straight up refuse. ACKS Tampering with Mortality rules are in use, so you might not come back quite right.
- How are replacement PCs handled?
As efficiently as possible. Henchmen can be promoted. Strangers can be met on the road. Re-inforcements picked up in town. Meta-game rule is that new characters are accepted initially. If they subsequently make themselves unwelcome, that’s on them.
- Initiative: individual, group, or something else?
Individual, but groups of undifferentiated NPCs/monsters might all just get a single roll.
- Are there critical hits and fumbles? How do they work?
1 always fails. 20 always succeeds. If you have Weapon Focus, 20 is double damage. There’s also cleaving — and it doesn’t require a proficiency.
- Do I get any benefits for wearing a helmet?
You don’t get a hole in your head. If you don’t wear a helmet as part of an armor that should have one, your AC is one worse.
- Can I hurt my friends if I fire into melee or do something similarly silly?
Yes, unless you have the Precise Shooting proficiency. Details here.
- Will we need to run from some encounters, or will we be able to kill everything?
You don’t have to run. You can stay to fight and die. It’s up to you.
- Level-draining monsters: yes or no?
- Are there going to be cases where a failed save results in PC death?
- How strictly are encumbrance & resources tracked?
Strictly. Though ACKS encumbrance rules are fairly lax, really. You count stones: one big item is one stone, six smaller items are one stone, 1000 coins are one stone.
- What’s required when my PC gains a level? Training? Do I get new spells automatically? Can it happen in the middle of an adventure, or do I have to wait for down time?
XP is given out when you reach safety, so you never gain a level in the middle of action. No training. Spellcasters mostly get spells automatically — at least on lower levels.
- What do I get experience for?
Treasure and monsters. Primarily treasure. Dungeon stocking has 4:1 ratio in gold/monster XP.
- How are traps located? Description, dice rolling, or some combination?
If you do something that would reveal the trap, you find it. You can also roll.
- Are retainers encouraged and how does morale work?
Henchmen are a big part of the game. Morale and loyalty rules are in use.
- How do I identify magic items?
There are proficiencies that allow that. In town you can show your stuff to a sage. A 9th level mage can research a magic item. There’s also always trial and error.
- Can I buy magic items? Oh, come on: how about just potions?
Yes. Even minor potions are pretty expensive, though, and availability is not guaranteed at all.
- Can I create magic items? When and how?
Starting from 5th level. RAW.
- What about splitting the party?
If you want to.