Hi :)
I'm a big fan of the original Vampire:The Masquerade setting and I wanted to play it with a system that actually worked ... so I'm trying to use the SS to that end, and I'm searching for suggestions and advice.
Here is what I came up untill now...

- General Rulings -
To keep vampires inherently above the human standard there is a veto on any Secret that allows a character to spend more than 1Pool on a test ... Vampires have ways to obtain such powers, but other than that it is a forbidden effect.
(other supernatural creatures may have their own ways of breaking this limit, obviously)

Vampiric "Generation" will be something completely aesthetic and freely chosen, with the whole table as a judge for what's appropriate or not.
Beside that, the power that can be acquired by consuming the blood of a more ancient/powerful vampire will be represented by a cumulative Secret.

- Pools -
Pools have been re-skinned into:
Blood (was Vigor)
Will (was Reason)
Beast (was Instinct)

- Abilities -
I'm still working on a starting Ability Landscape, but beside the obvious "skills" I thought about converting as Abilities both the old social "backgrounds" (Resources, Contacts, Allies/Influences, etc) and the vampiric Disciplines.

And about Disciplines...
Each vampire has access to the 3 specific Disciplines of his Clan, as Abilities at Rank 0.
Each Discipline allows him to use it in the fiction, tapping into a wide range of powers and effects ... for example ... with Animalism you are able to speak, command and summon animals, with Obtenebration you can manipulate and summon a sort of semi-liquid darkness ... then with specific Secrets you get access to more complex and advanced powers, like turning your body into darkness, or improving the skill-set of an animal you are commanding.

You can improve in-clan Disciplines as normal Abilities, while out-clan Disciplines are normally unavailable.
To get out-clan powers you need to do one of two things:
1) get a teacher and buy Secrets ... basically you need 1 Secret to start manifesting the new powers, then 1 to get access to every rank of the Discipline/Ability (I'll show the Secrets later)
2) do a Diablerie ... this way you get a Secret that allows you to learn out-clan powers with much less hassle (I'll show the Secrets later)

In this regard all forms of Blood Magic work like this: there is no "general" blood-magic-Ability ... no Thaumaturgy, no Necromancy, etc.
These things only exist as abstract concepts that define what kind of magical tradition you tap into.
The true powers, the actual Abilities, will be the specific "Paths" and "Ways" ... of which you choose one as "primary".
Simply put your 3rd Discipline will be this one Path/Way ... and all others will count as normal out-clan powers for which you need a teacher and extra-effort to learn and master.
So for example a Tremere character may have Dominate/Auspex/Creo-Ignem and another one can have Dominate/Auspex/Movement-of-the-Mind, and so on.

Rituals simply translate into Secrets.

- Keys -
Every vampire must have some specific keys.
The free starting key will represent the bestial vampiric nature (Key of the Beast).
Another key MUST be acquired with the starting Advances, and this one has to represent a "Moral Path".
Other than that, Keys work the same as basic SS.

Key of the Beast
01xp: each time you let the Beast emerge, even with little (but evident) details, gestures and instinctive reactions.
02xp: each time you "lose control" and fall into Frenzy or Rotshreck.
05xp: each time you sacrifice your immediate interests to fall into Frenzy or Rotshreck.
10xp: BuyOff - you reach Golconda and free yourself from the afflictions of the Beast
(supposedly this would require a Transcendent result ... this buyoff is in place to preserve the orthodox Key structure and to provide a bit of color)

Path of Humanity
01xp: act in a selfless and compassionate way, or choose a non-violent alternative solution to a situation.
03xp: act humanly (as defined above) even in the face of personal danger or harm.
10xp: BuyOff - leave your Humanity behind and become a soulless monster [this Key can only be replaced by another Path]

Path of Blood
You are a fanatical follower of Haquim's teachings; all non-Assamite vampires are flawed and inferior creatures whose sole purpose is to give their blood to let the Assamites get closer to Cain, or to help them in pursuing their goals in the name of Haquim.
01xp: act in a "racist" way toward infidels; express your beliefs.
03xp: convert an infidel to the Word of Haquim, or Diablerize him if he rejects the Truth.
10xp: BuyOff - leave your faith in Haquim and become a soulless monster [this Key can only be replaced by another Path]

I'm working on the other traditional Moral Paths too, both from the Masquerade and Dark Age books ... and obviously any player could devise his own Morality, with the table's approval.
The point is to fix the idea that vampires NEED a defined code of morals to not fall prey of the Beast ... one can end up with 4 Keys in use and the 5th one closed off because he prefers not to have any morality.
Obviously we came up with other Keys too, but they are not Moral Paths ... they are just pre-packaged options that a player may pick if he likes them :)

- Secrets -
Here are some secrets we produced that we felt were needed to the functionality of this adaptation.

Secret of Discipline Learning
Prerequisite = an active teacher
The vampire obtains the Discipline at Rank 0, but he's still unskilled in its use and can only invoke the powers in a cosmetic and minor way.
Using this minor powers in a test earns 1 Penalty Die.
The vampire can push his limits and use the full extent of his newfound powers, but each use/test costs 1 Pool.
(or it may earn 2 Penalty Dice for the normal/major use of the power, instead of requiring a Pool cost ... suggestions?)

Secret of Discipline Training
Prerequisite = an active teacher
Prerequisite = Secret of Discipline Learning
The vampire can acquire and normally use this Discipline up to a rank of 0.

Secret of Discipline Adept
Prerequisite = an active teacher
Prerequisite = Secret of Discipline Training
The vampire can acquire and normally use this Discipline up to a rank of 1.

Secret of Discipline Initiate
Prerequisite = an active teacher
Prerequisite = Secret of Discipline Adept
The vampire can acquire and normally use this Discipline up to a rank of 2

...and so on with the Secret of Discipline Expert and the Secret of Discipline Master.

Secret of Diablerie
Prerequisite = having perpetrated a Diablerie
This Secret is forced on the character right after the act of Diablerie and produces 3 effects...
1) select one of the three in-Clan Disciplines of your victim and note its name near this Secret; you don't need a teacher to learn this Discipline's secrets of Learning and Training, nor you need further secrets to develop it beyond rank 0.
2) if the victim had a number of Secrets of Diablerie greater than yours, you get the (cumulative) ability to spend +1 Blood on pertinent tests; note the "+1" near this Secret.
3) from now on your aura shows a black strain that represents what is left of the tormented soul you just consumed; note the name of your victim.

So this Secret may end up looking like this: Secret of Diablerie (Fortitude / +1Blood / Vincent LaCrosse)

...

Comments?

...

Now, about a problem, I am unsure about how to handle Aggravated Damage.
I read on this forums about Aggravated Harm, and it sounds great, but I am troubled by something...

In the Werewolf thread Eero suggests a couple of ways of handling this, like the Silver Imbuement or the Secret that allows the character to inflict AH on a specific kind of creature.
My problem is that both this solutions seem to be "balanced" by being very situational ... you get no particular benefit if you use a silver weapon against a non-Lycantrope (in a dark world where YOU and mostly your fellows are were-creatures), nor you get benefits from you Secret if you go against the wrong kind of creature (in a fantasy world were there are many kinds).

But what about supernatural claws?
They just deal "really bad damage" to... well... anything :P
Such a power would be too good.

Maybe a steep Pool cost may rebalance it?
Like spending 3 Blood to summon the claws for one scene?
Or a smaller but constant cost, for things like hurling fireballs (the Creo Ignem thaumaturgy power) ... like 1 Will per use?

And what about a "skill" prerequisite?
Like... with the Protean powers you can have claws (uuh scary!)... then with a Secret you can have this claws deal Aggravater Harm (Blood) but only if your Protean ability is at least at rank 1 or 2.
My concern here is that, in theory, Solar System ability ranks are meant as "narrative weight" and not as "skill levels".

Any thoughts about that? ^_^

First of all, I like what you've got here. It makes immense sense to limit mundanes to a Pool cap of one point, that's how I'd do it in WoD, too.

I could see making Generation a crunch issue, but that's just me thinking that it's a big deal in the setting - I'm no expert, and have in fact quite limited exposure to WoD in general. If you wanted to make Generation a thing, you might consider simply saying that a high Blood Pool is the same as a powerful Generation in the fiction. You could even reflect this with wacky rules for creating new vampires... unless I misremember, VtM vampires got their generation directly from their sires, so you could say that each new vampire gets a Blood Pool at one point less than their sire. (For chargen this would simply establish the sire's potency by having the player set the Pool, but later it might matter more.) This would give us some interesting benchmarks to reflect on (not rules, you understand, just some flavour to taste), such as defining the thin-blooded generation as being those vampires who only have a Blood Pool of one - they can't sire anymore. And Caine... he'd probably be around 10-15 or something. In fact, you could just go exact and have it be 13; unless I misremember my VtM, there are 12 generations between Caine and the time of the thin blood.

(Again going by memory, VtM vampires get more generation by diablerie, a high crime. I wouldn't worry about mapping from fiction to mechanics too closely in this, even if I suggest drawing some parallels between a high Blood Pool and generation. Exceptional vampires, like player characters, might have some other reasons for their high blood potency, unless the player likes the idea that pushing an Advance into Blood is explained as secret murder.)

In comparison, when I wrote vampire rules for the Finnish TSoY, my vampires started with a one point Blood Pool that came on top of the mundane Pools. I'm rather happy with the idea of a separate Blood Pool, and will be publishing those rules as a sort of preview for my TSoY book when I get around to it.

Along those lines, now that I'm thinking of it, it wouldn't be entirely out of line for WoD to say that all characters, mundanes included, have the Pools of Will, Experience and Contacts, while a supernatural creature like vampire could have an extra Pool. I might do this instead of what you suggest because I'd want to have solid baseline rules for how to handle mortals. Having a mortal with a "Blood Pool" seems a bit unsensible to me. If I did it this way, then Blood would only directly deal with purely vampiric things, while stuff that mundane people can do would be covered by one of the other three Pools. I also like the idea that a character can begin with more or less vampiric potency, as the player can distribute his Pool points into mundane resources.

As for Abilities - yeah, Disciplines definitely need to be Abilities. In fact, I'd probably forgo conversion and just say that they'll map 1:1, with adjustments made in flight as necessary. A part of the fun in switching systems like this is the fruitful tension of negotiating with the setting and the rules, and I can already imagine that it'll be fun to figure out the new implications of the rules-set regarding some weirder disciplines. Should something seem unworkable, it's easy enough to fix it on the run.

Other Abilities... Well, I'd probably do some combining from the WoD skill list to get to something like 5-10 mundane Abilities, ideally so that they all end up fun and impressive. Combinations along occupational or background lines, perhaps. Also, backgrounds can be Abilities as well, just as you say. Those will probably require some care in figuring out how to implement, but that'll come to you once you get the other parts of the conversion nailed down.

I'm with you regarding the implementation of the Disciplines, good stuff. I like the idea that they'd all be Blood-connected Abilities. Requiring an extra Advance for each level of an out-of-clan Discipline seems somewhat heavy-handed to me, though; one Advance is good, but more than that seems like you don't really want to allow that option. I can see how a VtM player would move heaven and earth to get to the kewl powerz, but I don't know if that'd work so well in Solar System - all Abilities are just as good at winning conflicts, so if you put a too high price tag on learning them, you actually smother the natural, fiction-based leanings the players have. Then they won't get the out-of-clan Ability even when it'd make sense for the character.

How about this:

Secret of the Blood (clan)
The character is a vampire of a particular descent. All vampires have this Secret, which gives them a Blood Pool equal to one less than their sire, the character from whom they got this Secret in whatever the VtM name for that vampire-making ritual was. Each vampiric clan comes with a weakness (an extra penalty die in certain situations) and three Disciplines they can learn freely. In addition, all vampires suffer a penalty die for everything they do during the day, and burn up in direct sunlight, and whatever else there was to the default VtM vampire.

Secret of Mentor
The character has a mentor willing to help him out in various ways. Specifically, and most relevantly for our purposes, this mentor trusts in the character's designs enough to teach him forbidden and/or esoteric knowledges. To be explicit, this includes vampiric disciplines, which are by default not taught to others without a strong bond of this sort, signified by a Secret. In other words: you can get out-of-clan Disciplines, but you need to pay an Advance for the source.

Secret of Diablerie
The character has killed another vampire by drinking their blood. If the other vampire had higher Blood, he gains a permanent point of Blood Pool. Furthermore, he can learn any Disciplines and Secrets the victim knew by expending Advances normally. Other effects to taste - the character might get personality flashbacks to the other guy or something, unless I misremember VtM.

For blood magic, what you sketch out seems sensible. Will the players be experts on WoD? My own reaction would indeed be to keep Thaumaturgy as one Ability, unless the group in general was well versed in VtM lore and actually cared about the differences between the magical schools. If the players are at all superficial about it, I could imagine this as a sort of needless limitation on creativity. I know next to nothing about VtM magical schools, but if they're like magical schools in every other game, then their differences are mostly just different ways of getting the same thing done. For the situations where this is not the case, you could have Secrets. Something like this:

Master of [whatever]
The player can spend unlimited Blood in magical rituals concerning this specialty.

Your Key scheme looks nice. I could see making the Beast thing a Secret that messes the character up horribly unless he has a moral Key, just to make room for play without a morality, but at a price, and only for a short while... Ah, what you need is this: the Moral Paths need to rejigger the Pool refreshment conditions for the character, so that only the humanity-pathers have the same ones that humans do. Others have the sort of crazy monstrous things those paths advocate. This way the choise of path gets a bit more teeth.

--

Anyway, just some random thoughts. Now onto your question: you could balance the aggravated Harm mechanic I outline in World of Near by giving it a Pool cost per use... two Pool is probably pretty good, or one if you want to make the power bad-ass. Three for the whole scene is also entirely reasonable, I like that. Magical claws don't sound very aggravated to me, though - you might be better off with just a bonus die to a check, or an equipment bonus.

I've done the Ability prerequisite thing in Solar System, and it can work. Normally I wouldn't recommend it due to how most of those limitations are really not that necessary (and just like you say, sometimes it's fruitful to disregard the Ability rank in narrating a character's in-fiction skill level), but as I wrote above, part of the fun in this sort of thing is to play jazz with the original and new rules and see what they do together. Therefore I'd probably milk the VtM Discipline power ranks for all they're worth, and indeed limit characters to their Ability rank in which powers they could get. I wouldn't do this for any other Secrets in the game, either, just the discipline powers. There are five Ability ranks in this game just like Vampire, too, so conversion will be easy. As SS doesn't even care about balance, you can just glorify in the weird solutions VtM has, play fully and see what they do without intervention. Sounds interesting to me, I imagine that some powers are much weaker and some much stronger in the different context and with different concerns that SS has. It's all good, though.

(Don't sell non-Discipline crunch short in this process, though. For instance, many vampire powers are such that I wouldn't necessarily have the player make a discipline check as his primary check in a conflict; rather, perhaps he can just support a normal Ability. Great strength is a good example here, what's its name... Protean? Fortean? Something like that. Anyway, I'd also create a few mundane, mortal-type Secrets just to balance the vampiric thing a bit and remind the vampires that humans are not just prey. That's probably just my own leaning though, not anything VtM is about.)

First of all, I like what you've got here.

i forgot...

About Blood Magic
The original rules were terribly unbalanced...
you had 1 magical Discipline, with did nothing on its own ... with it you had access to rituals, and to other "mini-Disciplines" (the Paths and Ways) ... this mini-Disciplines costed much less, but actually they were full fledged 5 dots disciplines.

I thought of translating the basic blood-magic discipline as a container... a "school of magic".
So Tremere have access to the school of Thaumaturgy
Giovanni have access to the school of Necromancy
Tzimische Kouldun have access to the school of Kouldunism
etc

each school allows you to pick disciplines from its own pool... so a thaumaturge can learn "Movement of the Mind" but not the necromantic "Path og Bones" not the kouldunic "Earth Way"

Basically you function as any other vampire... you just have a slightly broader selection of starting disciplines, but otherwise nothing uch changes ;)