Five VS three VS one: Saving throws

First we have the classic five:

Death/poison

Wands

Paralysis, petrification

Breath attacks

Spells, rods, staves

- They look like omens on your character sheet. They put you into the mood of what the game is about.

- The saves are disconnected from actual traits of your character in-game. Your fighter doesnt train really hard to be resistant to Spells, he just does it somehow, which is ultimately up to the GM to narrate.

- If you think about it, saves represent how likely is your character to get plot armor. The Death Ray is not supposed to fail a % of the time, it just fails when it strikes your character because it suits the plot. There you find that D&D has a narrative side under its naturalistic appearance. Which is OK.

- As a good plot armor device, they increase only with level. This means that the more you play a character (the more invested they have been in the story) the more protected they will be from unwanted disasters. Sometimes, of course, the save fails.

- Though they sound cool, some effects can be hard to adscribe to those categories. Here is a guide, in which it is described how they are ordered from easy to hard, based on how lethal and telegraphed the effects are (because Gygax cares for you). BUT in my opinion, there is a lot of work and text space dedicated to saves in the book, while the differentiation between the highest and lowest saves are not very meaningful (+4 in the greatest cases). There are whole matrixes dedicated to check which is the save of a certain class, at a certain level, for a certain danger; and at which levels should they ever change. This makes it seem like there is an intended and important order for this, while the impact on the actual game is relativelly low. One could think that this granularity is excessive, and, while is not hard to check a number on a chart, ponder if it pays off. 

- Sometimes attribute bonuses might modify certain rolls. Many people is against it, but I feel that its just a small bonus after all and it helps to establish game reality: it is just tangible that a character with good dexterity can use its bonus when the save is reflex-dependant. As an alternate view, I was using a certain retroclone recently (Aventuras en la Marca del Este) which gave the Wisdom modifier as a bonus to ALL saves. Not bad idea at all in my opinion: wisdom is often despised unless one is a cleric, and though the increase in saves might be small, the increase in character depiction is huge: Your character is not just a faceless level 1 stick figure: its a moderately wise guy which happens to be 5% better at saving: that makes you start the game like a 70s pimp

The three saves (Fortitude, Reflex and Willpower) came later.

- They are level-independant, relying on attributes. Into the Odd (using strength, dexterity and charisma) went as far as removing the levels completely. This makes them more naturalistic and easy to adscribe to effects.

- This, on the other hand, removes the concept of saves as plot armor. This is the greatest departure point, in my view. You don't have to come up for a reason to "why" or "how". You also can't, because the save does it for you. Its an upside and a downside at the same time. Into the Odd, again, solves this on a very clever way: Strength is about enduring physical stress, Dexterity about reacting fast and Charm encompasses plot armor, as being a measure, among other things, of how much blessed you are. So you can always fall back on that to factor plot armor back into your rules.

- They are usually mocked on the OSRsphere mainly because they put weight on the attributes and because they don't scale with level (edit: as pointed by JEL in the comments, in 3e the saves do scale with level. I don't know to which extent as all my 3e knowledge is second hand). It is true that I don't think that they can be used as "roll d20 under this to save". The numbers are just too high: Level 1 characters with normal stats would save most of the time. Would be a joke. Into the Odd, AGAIN, solves this on a clever way by introducing attribute damage: certain attacks decrease your attribute scores, and then force you to save under them. I like how Chris McDowall has taken its way into exploring the three saves into a very fruitful design, turning them into attributes themselves.

- As the "don't scale with level" thing: we'll, that is a bad idea if we see saves as plot armor. But if we see it as a naturalistic simulation, it's ok. In the end they work if you are conscious on what kind of story you are emulating. 

The Single Save is a number that increases with level. 

- The number can be universal or fixed by class. A good example of it is Swords and Wizardry (class based) among the retroclones, and Pits and Perils if you go a little beyond that (universal, though dwarves get a bonus).

- This is freeing enough that you can give or take small bonuses on an easy way. It is easier to write on your sheet a single number with "+2 vs magic", like S&W does with Magic Users, than five of them, and then decide which one apply everytime. You can give each class a bonus to a specific situation: +2 vs death to clerics is also on S&W. +2 to reflex rolls to thieves? sure, just say it so. The best of the single save is that you don't have to come up with categories of saves prior to play. You can specify as much or as little as you want: You can make an amulet of +2 vs Sleep, for example; or a cheap charm of +1 vs storms, and drop them on your treasure.

- On the "saves as plot armor structure", it works perfectly without having to separate plot armor by "categories vs classes" that might have sense for Gygax, but seem arbitrary to me.

- You can set saves at a middle point between death (low) and spells (high) and just give +2 to -2 bonuses on specifics, using the classic saves as reference or set by you.

- You can also add attribute modifiers to it (from dex, cha, etc) in the same range of modifiers without it altering too much the math, but in a meaningful way, that makes players feel that their dexterity or charisma actually work.

- Single save is the best and everybody knows

and tomorrow, I will (try to) write how I am doing saves now in D6D  A.K.A. Trow Fortress. Thanks for reading!

EDIT: there is still another way to make this: with ZERO saves.