Advancing Skills With Use in OSR Games

For use in conjunction with any skill system really, but designed with the Histories system in mind. 

I really like the idea of skills advancing with use, as in Call of Cthulhu.  I've been brainstorming how to make that work in an OSR system using a loosely D&D-derived ruleset, and here's what I came up with.

When you use a skill and come really close to succeeding/failing– meaning what you rolled was really close to the DC– you get a tic next to that skill.  The skill gains a rank when it gets a number of tics equal to the next rank, so two tics to get to rank 2, etc.

How you get tics depends on the system you're using.

If you're using a die system that has a central tendency, like the 2d10 in the game I'm working on or 2d6 from Stars Without Number, you get a tic if your roll is very close to the DC.  In a 2d10 system I'd say you get a tic if it's equal to the DC or one higher or lower, while in a 2d6 system I'd say only if it's equal or one lower, to adjust for the narrower range of possible rolls.

I think this concept works better with dice systems that have a central tendency because it means you're more likely to get a tic if you make a test that you have close to a 50/50 chance of succeeding at.  That mirrors how skill learning works in real life, in that you learn the most from doing things that are moderately challenging.  IMO this is an improvement over the Call of Cthulhu system, where you just have to succeed on the skill roll and are therefore incentivized to look for chances to make easy rolls.

If you're using a d20 this gets harder– maybe something like you get a tic if you roll within 1 either way of the DC, and the raw d20 roll was 12+, meaning you had a less than even chance of making it.

If you're using x in 6 skills, you get a tic every time you roll a 1.  In this case you should also slow down skill advancement, which I'm about to talk about, since x in 6 absolutely needs a hard cap at 6.

I haven't tested this yet so I'm not sure how fast skills would rank up in practice, and it obviously depends on the lethality of your system.  There are three ways you can adjust that.

First, adjust how many tics it takes to get to advance a skill.  Maybe new rank x 2, or new rank +2.

Second, change how hard it is to get a tic.  Maybe you need to hit the DC exactly, or maybe you can come within 2 of it.

Third, you could make tics provisional and require them to be "confirmed" next time you rest.  Once you have a tic next to a skill, the next time you rest, roll a d10 (if you want skills to max at 10, or a d6 if you want them to max at 6 etc) and if it's higher than the skill's current rank, the tic is confirmed and you can now earn another one, otherwise erase it.  This also puts a cap on skill ranks.

Other than that, you need a way to have people acquire skills in the first place.  The three options I see are to either
a) have the first rank, or maybe just rank zero, be acquired through your class/level
b) have skills be acquired through play independently of class and level like in this system
c) have a set skill list, and every skill can be used untrained for at least some purposes in order to get that first rank

Finally you probably need a way to bolt this onto an existing system.  That's easy if every class is meant to have an equal number of skills, as the one I'm working on does.  Otherwise it takes some balancing.  It also depends on whether "skills" includes stuff like attacking or spellcasting, or whether you take the traditional route of skills being separate from attacks, magic and the like.

If you wanted to bolt this onto a system where skills are normally the province of one class over others, you need to give those classes advantages at it.  Like make them need fewer tics, or qualify for tics more easily.  Maybe also make them get rank 1 skills more easily.

One final note: if you use this skill system for combat skills like swords, guns etc, you may think it's a problem that those things tend to get rolled repeatedly, thus making it easier to get tics.  You could counterbalance that by making the requirements for a tic more strict for attack roll skills and anything else that tends to get rolled several times in a scene.

However, I don't personally plan to do that.  My thinking is that yes, combat skills can rank up faster, but they're also inherently risky to use.  High risk high reward live fast die young and all that.  This is why soldiers can be considered battle-hardened after only a few months of combat experience when most skills take years to master– you learn fast in combat, but also there's only so much combat you can get into before the odds against your survival become overwhelming.  Food for thought.

Anyway I'll give this a try once I get the chance, which might not be until next year, and when I can I'll do a follow-up post about exactly how I ended up doing the math to make it work.