Ziggurat Zagger
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Joined: Friday, 25th November 2011, 07:36
Draft guide to Crawl's time system
Time in Dungeon Crawl: Stone Soup
Although Crawl is turn based, it nevertheless has a time system which tracks how long has passed in game, and many actions have different durations, which may result in players unexpectedly getting smashed to death if they do something unwise. Let's start with some terminology:
AUT: Absolute unit of time, this is the actual time unit of dungeon crawl, and is not really mentioned in game very much at all. It is referenced in game by various other terms such as "delay" or "time". If a weapon has an attack delay of 1.3, this is equal to 13 auts. For example, here's a club:
Base accuracy: +3 Base damage: 5 Base attack delay: 1.3
This weapon's minimum attack delay (0.6) is reached at skill level 14.
The base attack delay is 13 auts, and every 2 skill levels reduces this by 1 aut, until it reaches 6 auts at level 14. The delay is shown in turns, our next term...
Turn: The most ambiguous of crawl's time nouns, a turn is typically considered to be 10 auts, but this is NOT consistent. Standard races move at 10 auts, and many actions also cost 10 auts, such as casting a spell, using scrolls/potions, etc. But, many other actions don't cost 10 auts: nearly all weapons have min delay below 10 auts (the dark maul and crossbows being the exception), movement on faster or slower races (or while hasted/slowed), walking into shallow water, changing jewelry (only 5 auts), etc.
Action: Something that the character does in game; making an attack, moving, casting spells, etc. This is what is counted when it comes to scoring, despite the morgue file displaying this:
The game lasted 04:48:51 (82118 turns).
What is actually counted here is actions, and not turns. Someone should really update the morgue generation code!
Monsters & the Energy system
So, you've taken an action which lasted 10 auts, what happens next? Every monster in the game has an 'energy' value, which is not displayed directly but is what the description "It is fast" is based on. The default value is again 10, which matches the 10 aut movement speed of humans. So when you move (10 auts), the monster gains 10 energy. Then, all visible monsters who have enough energy to act (always 10 energy), will take actions until their energy is below 10. If a monster has more than 20 energy, they will act twice. Note that energy is thus inverted from player movement speed, a naga moves at 14 auts (slow), but an orb of fire has "speed" 15, which means that it gains 15 energy every 10 auts, which makes it faster, not slower. Speed is a term used somewhat interchangeably with energy, which usually isn't used in game.
While any action like attacking or casting spells by a monster always takes 10 energy, movement is slightly different in that it has a 1/3 chance of taking only 9 energy, 1/3 chance of 10, and 1/3 chance of taking 11 energy. This is called energy randomization, and means that if you are running away from a 10 speed monster on a 10 speed race, you'll randomly either gain or lose a tile between you. This can be exploited by pillar dancing, waiting for the monster to fall behind, and then escaping up stairs. You may take a hit first as the monster randomly gets closer to you, but given enough time it will eventually fall behind as long as you don't die to the attacks from it when it gets ahead.
Let's give an example that isn't 10 speed, say a Naga who walks towards an orb of fire. The Naga takes 14 auts, or 1.4 turns, and the orb of fire gains 15 energy per 10 auts, so 15 x 1.4 = 21 energy gained. This means the orb will always get two actions in response, and could possibly get three, if it started with 9 energy. In cases where the energy gained isn't a whole number, the fractional energy is randomly rounded. For example, if that Naga moves towards a Cyclops (speed 7), it gains 1.4 * 7 energy, which is 9.8. This has an 80% chance of giving 10 energy, and a 20% chance of giving 9 energy. It is not possible to have fractional energy or auts in crawl.
Some monsters have energy modifiers for specific actions. A common one is to have a different swimming speed, for example hydras are speed 10 but have swim: 60%. This means if they are in water (shallow or deep), movement only costs 6 energy instead of the 10 it normally would (before energy randomization). A less common mechanic is the Juggernaut: a speed 15 monster (very fast) who attacks at a huge penalty: 450%. Thus they are hard to run away from, hit for a lot of damage, but don't actually deal a great deal of damage over time (relatively speaking, they are still quite dangerous).
Regeneration and AUT/Turncount Speedrunning
One of the quirks that arises from all of this is something called bread swinging, the practice of trying to intentionally take slow turns so that you can regenerate more health/mana per action. Since you regenerate health based on how long has passed since your last action, taking very slow actions means you will heal faster. The name bread swinging comes from it previously (I think it's been changed?) taking 15 auts to swing anything that was a non-weapon, but many other slow actions can also be used. Swinging with a 2h weapon that you have no skill in, walking into shallow water, walking while worshipping Chei, etc. Removing/wearing body armor takes several turns, but this is implemented as taking five 10 aut actions, rather than one 50 aut action, and so it doesn't work for this.
This is one of the major reasons why Cheibriados is generally the best god for speedruns, as it's very easy to simply walk at 20 aut delay, and effectively double your regeneration per action. In addition, Cheibriados gives a rapid power increase which promotes being able to dive to more dangerous levels quickly; while the downside of not being able to escape doesn't matter much when your goal is only to win one game out of hundreds. And remember that despite the morgue lying about how many *turns* you took, it's actually counting actions. Some players have suggested changing to aut-based scoring (whether you call it auts or turns), but in my opinion, this isn't actually fixing anything, and is just changing one set of problems for another set of problems. It would also change what kind of weapons are optimal to use, allowing for things like quick blades to be more time efficient (assuming they actually deal enough damage to kill in a low enough number of hits) than slower, 7 aut min delay weapons. Currently, crossbows (10 aut delay) are a more ideal speedrun weapon than something like a demon whip (5 aut delay), although actual speedrun strategy usually centers around using highly efficient spells (Borgnjor's Vile Clutch, Statue Form + unarmed, or summons such as Summon Horrible Things).
*end of guide*
Anyways, looking for anything you feel should be added, is the speedrunning stuff relevant or offtopic, am I a horribly biased Cheibriados fanboy, etc etc...
And what does happen if you have a 14 aut turn and a monster has 8 speed, gaining 11.2 energy? Random rounding to nearest integer? Added
Officially ruining greatplayer statistics since Jan 18th, 2015.
I wrote the Melee Naga Guide.
Recording of my 15 rune 40k turn VSMo^Chei speedrun!