What about additional magic skill points? You`ll get them when using magic and can use them tho get new spells and combine/change/boost spells you already have.

Can I still use the active skills where I have permanent levels when I don't allocate SP on them? The XP to get permanent levels on a skill would be always be the same or they change according to the current level? Do I need the SP to be able to get permanent levels? The passive skills can be improved with permanent levels?

The first point (no pun intended) goes against what I would think of as natural skill learning. For example, in real life I can't un-learn how to ride a bike so I can then insta-learn simple sleight-of-hand tricks. Yes, I know: games come with a built-in acceptance of disbelief and twists on reality, and game mechanics require compromises to realism.

So I think maybe for point 1 to be plausible (taking back a point), the character should not use that skill for a certain amount of time - to simulate the natural gradual degradation of the skill through lack of use - before being allowed to unlearn a point. And I would not allow that new point to be spent on a skill where the player is at level 0 - they should already have at least one point in the skill, so it simulates them getting better at it by practicing in their off-time or other avenues of off-screen study.

I do like the 'increase by using' formula, though.

It's a bit simplified, but I like how some of this is handled in Mount and Blade: Warband. Your combat skills increase through usage, and you can also "buy" a few points when you level up. The other skills are increased only when you level up. The exceptions to "only" are found in a handful of skills for which you can purchase books to study over time, which accumulates only when you pitch camp, to gain a 1-point bump. I think there are 4-6 books like this, for things like Trade, Engineering, Leadership, and a few others. You won't find a book for Riding since that's something that book learnin' doesn't really fit, but Tactics does make sense.

The skill XP to get permanent levels in a skill depends only on the permanent level of that skill. For example, learning and leveling up Nucler Blast (which, let's suppose, is at the end of a long chain of prerequisite skills that do not include Heal) will not make it any harder to level up Heal or Party Heal.

You need to spend SP on a skill in order to use a skill before getting a permanent level in the first place, as the only way to get skill XP is to use the skill in question. For passive skills, the problem is defining what counts as a "use" of the skill, so it may not be possible to get permanent levels in them. (Also, there may be passive skills that you might not necessarily want active all the time.)

Also, one idea I have is to not have any notion of character level in the game, hence referring to a character's "current level" would be as meaningless as referring to Mario's MP in the original Super Mario Bros..

That rule would not work; in order to use a skill in the first place, you must have at least one skill level, and in order to get a permanent skill level, you have to use the skill. Therefore, skill points are needed to learn the skill in the first place, so disallowing them to be used on level 0 skills would make it impossible to learn any skills at all.

How about this:

The character starts with 1 Study Point. She can allocate this Study Point to any skill of her liking. As long as the Study Point is allocated to that skill, all the experience she gains goes into that skill. Once this skill reaches 100 XP (for example) it receives 1 Skill Point which is fix and tied to that skill. She can reallocate that Study Point any time she wants to any other skill, but only the skill that it is allocated to gains experience.

However, XP cost for any subsequent skill level is higher, for example your Heal skill could be like this:
Level 1 needs 100 XP
Level 2 needs 400 XP
Level 3 needs 900 XP
Level 4 needs 1600 XP
Level 5 needs 2500 XP (unlocks Party Heal)
Level 6 needs 3600 XP
Level 7 needs 4900 XP
Level 8 needs 6400 XP
Level 9 needs 8100 XP
Level 10 needs 10000 XP


Higher tier skills like Party Heal need 2 times or 3 times the XP of lower skills. For example:
Level 1 needs 200 XP
Level 2 needs 800 XP
Level 3 needs 1800 XP and so on

Furthermore, your character receives more Study Points as she progresses through the story, at important turning points in the main quest, maybe up to a maximum of 5 Study Points. She can spread these Study Points across several skills or allocate them all to one skill. The more Study Points are allocated to one skill the more XP it receives. (For example 3 times XP if 3 Study Points are allocated to it).

This definitely needs some testing on how many Study Points maximum should be available throughout the game, how much XP the character receives for each kill and completed quest, and how much XP the Skill Point gain costs.

This is an interesting idea, albeit quite different from my idea. In particular, I prefer having skills increase through usage rather than killing enemies or quest rewards.

On the other hand, one could combine the ideas in an interesting way; one could start with a study point, but also improve the skill faster by usage. Alternatively, the study point could come later; maybe it comes at a certain point in the game, or maybe there is a skill that grants the character a study point. Or, there could be a skill that grants the character a teaching point; if the skill that is assigned the teaching point gets used, everybody *else* in the party gets skill experience for that skill.

(One downside of combining these ideas; it takes more code, and there's a greater potential for bugs or balance problems as a result.)

Or Study Points could work in such a way that they transfer part of the XP gained to a different skill. For example:

The character starts with 1 Study Point and has it assigned to Ice Blast. The character uses her Heal skill, for which the Heal skill gets, say, 10 XP. However, since there is 1 Study Point assigned to Ice Blast, 10% of this XP is transferred to Ice Blast. So the character gets 9 XP for Heal and 1 XP for Ice Blast. However, if the character uses Ice Blast, Ice Blast would get an additional 10% of XP for its Study Point, thus 11 XP points.

Throughout the game the character gets more Study Points, up to 10. This allows her to transfer more and more of the XP to other skills, up to 100%, or increase the XP gain of a particular skill up to 200%, which I think is all quite useful for the endgame.

Then I think your premise completely depends on the skill list for the game.

Since all RPG systems are models of portions of the reality in the gameworld, I am trying to give this system a translation into world mechanics (mathematics into physical meaning, if you want). It might be understood as "focusing" your attention and training into different abilities.

You are considering only skills, not attributes at all? Like, one day you focus on healing and speaking in public; next day on fighting and jumping. With attributes, one day you would focus on being strong, next day on being smart.

For passive skills, you might be counting the time that they have been available, instead of actual usage. You might as well do it for ALL skills. After all, you would be training them, even if you do not use them. The problem of linking actual usage to skill increasing (a Lamarckian increase, if you wish) is that the player becomes LESS free to experiment with the character, and the system you describe seems to hold protheic change and adaptation, as well as playful experimentation, in high regard.

For me, I like that, maybe modern games are making us spoiled, but it is nice to experiment without having to wait to another full playthrough. You can still devote time and effort to develop your character, but if you do not have so much time to study the system, at least you can easily avoid the worst blunders once you realiza that the skillset you thought at first would be great is the worst combination since bubblegum and aprons. To put it in another way, nowadays, forgiving systems that allow you to learn from your mistakes WITHOUT having to restart are a good think (let those who want the absolute best ever combination restart near the end if they wish for one extra point in jumping because they realize they forgot to jump once at the beginning of the game).

Also, pen & paper or computer? If you want to use it with a computer you may make it a bit complex without having to worry about the players and master/game director becoming insane with the calculations. I guess you are thinking computer JRPGs mainly?

Nice thread.