You fail to memorise the spell

[Confidence Interval]

From curiosity as much as anything, what's the intention behind this type of thing?

"This spell is somewhat tricky to learn.
You fail to memorise the spell."

It's not clear to me that this adds much beyond minor irritation when you have to take multiple attempts to learn a spell - why is it not just a binary "You learn the spell" / "You do not yet have the knowledge to learn this spell"? Spells which are hard to learn are also hard to cast, which is where the true penalties (miscast effects) come in. Is there a reason why this is a stochastic rather than deterministic matter?

I can see an exception might be the high-level spells in which there's a miscast-type penalty for failing to learn a spell but otherwise can't immediately perceive why this is part of the game.

[jejorda2]

I've been saved a couple of times by learning cure poison with no poison magic skill, and once learned Insulate while electric eels were firing at me and orcs were blocking my retreat. I've probably died from poison while trying to learn cure poison half a dozen times.

If it were simply impossible to lean spells that are difficult to cast, you couldn't try that kind of thing. If it always worked once you had the skills, there would be no reason to learn some of the situational spells early. You might carry around the book with passwall in it instead of learning the spell.

Sometimes it is also nice to memorize a spell that takes ten tries to learn, then use that spell to get your skills up and cast it easily. If it just failed, and you couldn't find lower level skills, there would be no way to cast the spell instead of no safe way to cast the spell.

I like the system how it is.

I do wish that using ~ to repeatedly attempt learning was less prone to memorizing the next spell in the book when you press it too often.

[dtsund]

As I see it, repeated failures are the game's way of telling you "Hey, maybe you're not quite ready to start casting that..."

[ElectricAlbatross]

As I see it, repeated failures are the game's way of telling you "Hey, maybe you're not quite ready to start casting that..."

If that's the case, then disallowing memorization for a spell under a certain threshold of success will work just as well. "You feel that your magical skills are not yet sufficient to commit this spell to memory." or something like that.

The way I see it, spells that are at success Poor or lower are effectively useless. How about giving the above message when you try to memorize spells that would have success Very Poor or lower, and let memorization happen on the first try for the rest?

[Moose]

+1 for the binary state ... You should be able to either memorize it, or not.

It's really irritating when I roll and transmuter, and fail a couple times trying to learn fullsome.

If people think that spell failure makes makes a totally awesome mini-game of trying to learn Insulation when you have a swarm of Electric Eels firing upon you, then I suppose we could keep that around by making memorization interruptable by combat. I somehow, don't think this is an important scenario.

[galehar]

Hey, you know what would be fun? Miscasts!
Of course, then you could train skills just by carrying the book. And dangerous books would trigger stronger miscasts.

[dpeg]

As dtsund points out, having to memorise a couple of times is a very good (almost haptic) way of telling players what is going on. It is much better than "You will only cast this spell with [adjective] success. Memorise anyway? (y/n)".
Memorising spells is not a staple action (like eg. casting them, or eating, or travel etc.) I see no reason to change status quo.

[Tiber]

That's kind of shoddy reasoning. There are better, less annoying ways to warn users that they shouldn't mess around with spells with low success rates. And it's not like people necessarily go around spamming spells the moment they memorize them. It's often better to get a spell memorized so you can see how your skills affect its success rate, and so you don't have to run back to your stash to memorize it once you do have a good success rate.

[njvack]

Hey, you know what would be fun? Miscasts!

I'd actually support this

Or leaving it alone, as it's not really broken.

[evilmike]

I think there should be a --more-- prompt by default when you fail to memorize something.

Sometimes when I've tried to memorize a spell that is at Great or around there, I'll fail but just assume I memorized it successfully due to the decent success rate. 1000 turns later, I find out that the spell isn't in my list...

I'm not the only person this has happened to.

[varsovie]

I think there should be a --more-- prompt by default when you fail to memorize something.

When you fail such an easy spell or a moderate one that you just know you will use but don't want to carry the book, what I hate the most is that you should press at least three other key, sometime 4 (enter when to many notifications) just to re-read this spell.
And sometime it's fulsome distillation that you have to keystroke two or three time.

So yes a promp like

You fail to learn ******, the spell (seems easy/is quite difficult/is really beyond you knowledge). Would you like to try again? Y/N

Would be clear and save my M. ^^

[smock]

As dtsund points out, having to memorise a couple of times is a very good (almost haptic) way of telling players what is going on. It is much better than "You will only cast this spell with [adjective] success. Memorise anyway? (y/n)".
Memorising spells is not a staple action (like eg. casting them, or eating, or travel etc.) I see no reason to change status quo.

There's a chance that a spell with a low success rate is memorized on the first try. A more direct way to warn players would be to display a message to the effect of "At your present skills, foo's casting success rate will be excellent/terrible/etc."

[Grimm]

The verbal scale could be rewritten, as I've already done for the stealth and MR verbal scales.

[ElectricAlbatross]

That still doesn't fix the fact that you don't know exactly how likely you are to succeed in casting a spell.

Exact values for attributes such as MR and Stealth shouldn't be shown to the player because these numbers are checked against other numbers to determine their effect, so divulging them reveals no real information. That's not the case with spell success; it's a simple probability, so the player gains real, useful information from seeing it.

In addition, deciding when spell success is actually "good" (that is, good enough) is more complicated and depends on more factors than doing the same for MR or stealth: you need to take into account whether it's an attack spell you need to spam or a buff you only need once, what build your character is, how much MP you have left, how severe the miscast effect would be, what your alternative options are, and so on. Since the acceptable rate of success varies over all spells and even over different situations for the same spell, a static rating is completely unintuitive when it comes to giving players the information necessary for making effective tactical and strategic decisions. How many times have we had to tell a new player that "Good actually isn't good" or "Very Good actually isn't good enough for high-level spells" or "you should have foo at Excellent"? Better to show players the percentages so that they can decide what is good enough for their situation.

There are many numbers in Crawl that players benefit from not seeing; spell success rates are not among them.

[nicolae]

I think at the very least, it would be helpful to display the percentage range alongside the adjective. "Good (70-80%)" and such.

[dtsund]

I've offered repeatedly on IRC to port* the percentage indicator code from Light to Stone Soup, but it seems as though it's not happening. Interested parties can read resulting argumentation (starts about halfway down).

*The code is nontrivial; success is not based on an 'x chance in y' call.

[dpeg]

The Albatross has some good points. However, I think that percentages are too fine information. You generally want a range of up to 12 items. Also, a linear scale is not good, you want more information near the 100% extreme. One way to give the information would be as "Fails: one in [foo]". This would be a single number, but its meaning is easier read off (in my opinion) than a percentage.

[evilmike]

Showing fractions for failure rates (eg 1/10, 1/20) is probably the most idiot-proof way to convey that information, but percentages are a bit nicer looking (they take up less space).

I do think if percentages are shown, they should be failure rates and not success rates, though. 90% success and 95% success are fairly different: even though they are "only" 5% apart, the spell at 95% is half as likely to fail, obviously quite significant. Showing these numbers as 10% and 5% makes it a lot more clear.

Doing it this way is also far better than using some sort of log scale in my opinion. If a number is going to be shown, it might as well be the actual percentage, or something as close to it as possible.

These points were probably brought up in the irc log dtsund linked.

[rchandra]

I think there should be a --more-- prompt by default when you fail to memorize something.

When you fail such an easy spell or a moderate one that you just know you will use but don't want to carry the book, what I hate the most is that you should press at least three other key, sometime 4 (enter when to many notifications) just to re-read this spell.
And sometime it's fulsome distillation that you have to keystroke two or three time.

Let me save you some trouble, the repeat last command key is very helpful for doing this (or eating 15 strawberries). By default it is ` (backtick or backquote, shares a key with ~ tilde on a US keyboard)

[Danei]

How about making memorization (failed or successful) cause hunger ?

[sanka]

It's often better to get a spell memorized so you can see how your skills affect its success rate

I always assumed that memorization success rate is the same as spell success rate. And you can see memorization success rate if you have found the book, even if you do not have it (e.g. in a shop), by examining the book. (You can find the book by Ctrl-F, then examine it rather than travel to it.) Of course you are right, if you memorize it early, you do not need to go back to the stash and memorize it, thats true. If you have the slots, you are sure you want the spell, you may memorize it and drop the book.

Sometimes it's very useful to memorize spells that have Poor success rate in advance, if you have a couple of poitions of brilliance. It may change the otherwise not too useful potions to strong emergency items.

[Tiber]

I know all that. But that's kind of a pain compared to just hovering over the spell in the spell list.

[varsovie]

I think there should be a --more-- prompt by default when you fail to memorize something.

When you fail such an easy spell or a moderate one that you just know you will use but don't want to carry the book, what I hate the most is that you should press at least three other key, sometime 4 (enter when to many notifications) just to re-read this spell.
And sometime it's fulsome distillation that you have to keystroke two or three time.

Let me save you some trouble, the repeat last command key is very helpful for doing this (or eating 15 strawberries). By default it is ` (backtick or backquote, shares a key with ~ tilde on a US keyboard)

I use this key often with conjuration spells, never tough of using it with books. Thank you.