Arcane Game Lore

Notes for tonight's game: TPK!!!

Designing Out Loud – Choosing a Skill System

I mentioned in my introduction article that I had the idea for two games bouncing around in my head.  In truth they are mostly the same.  Almost all the mechanics would be the same in both systems with one or two possible exceptions.  The main difference is the choice of a skill and experience system.  (The other is probably combat).  I’m torn between two different models that I love.  Both have pros and cons.  In this entry I’ll be exploring those two systems.

This is an important choice as it can have repercussions throughout the game.  At the very least in the way other mechanics are described and in some possible cases the very way they work.  It has fundamental impact on character generation and how characters advance and improve.  If this aspect of the game was modular, I’d write up one as the basic system and have the other as an optional system.  I still might do that but I don’t think it will be possible.  It definitely isn’t possible to switch between the two.  Once you’ve started down one path it’s not really possible to switch to the other without completely revamping the character.

The one thing that is the same about the two systems is that they are both percentile based.  You have a change to succeed with each skill and you roll a d100 to see if you make it.  Beyond that, however, they are quite different.  So let’s dive in and start exploring.

Skills and Experience Points

This first system is inspired by the skill system in Star Frontiers.  In this system each character has a primary skill area (PSA).  Skills that fall in this area cost less, and therefore advance faster, while skills outside this area cost more and it much harder for a character to become proficient in them.  Each beginning level character starts with two skills, one from their PSA and one from any skill area (a second from their PSA or one from any other skill area).

The skills themselves are quite broad: Computers, Medical, Demolitions, etc. and each skill has a number of sub-skills: Operate Computers, Repair Robots, Diagnose Disease, Set Charges, etc.  This sub-skills will either have a based percentage chance or the base percentage will be based off the character’s ability scores.  Skills can be increased up to some maximum level (6 in Star Frontiers) and each level give you a 10% bonus to accomplish the skill.

A variation on this is to eliminate the sub-skills and just give a base percentage based on the character’s ability scores with the bonus for the skill level.  And the ability score used could depend on the task.  i.e. diagnosing a disease may depend on you intelligence while performing minor surgery may depend on your dexterity but both would use the medical skill.

Skill improvement comes by expending experience points (XP) gained through play.  With each level costing more than the one before (i.e. 4 for level 1, 8 more for level 2, 12 more for level 3, etc).  Players will typically earn 3-9 XP per session of play so early levels can be gained fairly quickly but the higher levels will take some time to acquire.


One of the biggest advantages of this system is that it is fast, both for character generation and during play.  On the character generation side, you can roll up a in just a few minutes.  In Star Frontiers, character generation takes exactly 5 die rolls, 4 for character abilities and on for starting money.  Other than that you choose a race and gender, pick your PSA and a pair of skills, and buy a bit of equipment with your meager starting fund and you’re off on adventure.  While I think my system will have a little more to it than that, the same principle applies.  You can pick your skills quite easily and be on your way.

During play it’s also quick to use the skill system.  Select the sub-skill you want to apply, find the base chance and add 10% per skill level, and add (or subtract) any modifiers given by the GM.  Then roll to see if you succeeded.


The existence of the sub-skill might also be considered by some to be a con as you have to remember what the sub-skills are and their base percentage chances.  The use of ability scores as the base chance and elimination of the sub-skills removes that issue but adds in the need for the player or GM to make a call on what ability score applies in a given situation.

Another less desirable aspect of this system is lack of differentiation.  One aspect of this is differentiation between different characters.  The skills are very broad.  Any character that has a computer skill can do all the same things that any other character with that skill can do.  The other aspect is lack of differentiation within the skill itself.  Is repairing a computer really the same skill as programming one or simply being able to operate one?  There is a bit of blandness in this skill system that just lumps it all together.

A third con, at least in some extent as I see it, is that there is no coupling between the experience gained and the skills that are improved.  Your character may spend an adventure hacking the computer systems of the rival gang and stealing all their secrets and then spend the experience gained from that session on his laser gun skill.  There is nothing to tie the XP to the skills used.  Now this isn’t necessarily a bad thing, and it works fine.  Plus if the GM wants they can place limits on what the characters can an can’t spend XP on but the system really allows it to go anywhere.  It’s a little unrealistic, you typically only get better at things you put effort into or use a lot and I like to see realism reflected in the game mechanics when I can.  So while I wrote the most words on this negative aspect, it may be the least important one.

Skills, Vocations, and Check Boxes

The second option I’m considering  is based on the skills in the Basic Role-playing System or, as I was introduced to it, in RuneQuest.  In this system you have lots of little skills: dodge, fast talk, charm, drive: ground, drive: air, first aid, repair computers, program robot, etc.  Each skill has a base chance that everyone has (maybe dependent on race) and then increases based on the character’s background and experience.  There are also modifiers based on your character’s ability scores that can increase or decrease your skills in broad categories (agility, communication, knowledge, etc.).

This system doesn’t have the concept of experience points or levels baked into it.  Rather each skill is just a percentage chance of success and when you successfully use a skill in a “critical” or meaningful way where failure has consequences, for most skills you get a “check”.  Then at some suitable down time during the adventure, you have a chance to increase your checked skills at which point all “checks” are removed and you can accumulate more.

Like in the other system, earning the higher skill percentages is harder than the lower ones.  In this case, to improve your skill you have to fail a skill roll, which, as you get better, is harder and harder to do.  This system also doesn’t have the concept of a PSA where skills in that area advance faster, every skill uses the same mechanics for improvement.

Additionally, this system carries with it the idea of prior vocations, what your character did in the years before they became adventurers.  Each year of vocation provides skill points (or possibly a skill list and number of points to use) to build up your character’s starting experience.  Thus if you were a machinist, you’d get one set of skills.  If you were a doctor, you’d get different ones.


No experience points!  This is a personal bias of mine but I really like the idea of no experience points.  I’ve never liked having to give them out or receive them based on some arbitrary judgment of the GM.  This is also a place where the realism can shine through a bit in that you can only improve the skills you use.  If you never once pulled your blaster during an adventure, there is no reason your character should get better at it just from surviving.  The system still allows you to increase unused skills via research or training but experience from adventuring only accrues in the skills you use.

Another area where this system shines is in character customization.  You want to be good hacking computers but not know a thing about building them?  No problem.  You want your doctor to specialize in disease and poisons but not really know about surgery?  Can do.  The more detailed skill lists allow you to customize the details of your character so that even if you are technician with a medical skill, the details will be different from someone else that chose the same idea instead of being generically the same.

This system also plays fast.  Your chance to succeed with any skill is just a percentage written on your character sheet.  Pick a skill to apply roll d100 and see if you succeeded.


This system would suffer from slower character generation.   With the larger list of skills, more thought would have to go into how to allocate your skill points when making a character.  Plus the vocations that define your background take some thought to pick, especially if there end up being a lot of them.  You’re not going to whip one of these characters out in 10 minutes.

Some would consider the large skill list a con as well.  It definitely means a large portion of the character sheet will be devoted to the skill list so that they are all represented.  Having to decide which of the skills apply to any given situation (or possibly more than one) can sometimes be a hassle or at least an irritation compared to just have a “computer” skill that covers anything related to computers.

Another con for this one is that it is a lot more work for me to set up.  Of course I like world building so it’s not like it will be drudgery but there will be a lot more effort expended.  Once done, it’s fairly easy to use, however, so that effort for the most part isn’t passed on to the players.

Last Thoughts

There really isn’t much more to say.  I like both systems.  One is definitely simpler and more abstract than the other but both are appealing in their own way.  The final decision will come later but feel free to chime in with questions, comments, or suggestions.

Categorised as: Game Design

One Comment

  1. [...] As I’ve been thinking about this, I wonder if character ability scores are something that should come early in the design process or something that should come later.  I also realized that this is one of those topics that are at least loosely coupled with the choice of skill system, which I discussed in my previous post. [...]

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