A first draft for RPG mechanics

While I barely have any existing skills with coding or 3D modelling yet, I have do have a lot of experience designing game mechanics for pen and paper roleplaying games. I've been working with and studying new rules system for over 15 years. This is the one area of game design where I feel highly competent, and I can create mechanics with intent, to achieve specific gameplay experiences. With lots of CRPGs that are clearly inspired by pen and paper games, I have a strong impression that the designers tried to simply copy pnp mechanics into a videogame format. At first because that's what they were familiar with from playing such games as a hobby or after work, and then later because that's how most of the existing CRPGs they knew did it. All the Dungeons & Dragons CRPGs explicitly attempt to replicate the D&D game mechanics as faithfully as they can while still being playable. Fallout was originally meant to be a GURPS game until the license was withdrawn during development and they created the SPECIAL system as a replacement. The early Elder Scrolls games used dice roll mechanics. And of course, the entire iso-RPG genre of the last 20 years exists as explicit spiritual successors of Baldur's Gate (a D&D game).

Evidently, this has served them quite well. But I personally argue that this has really always been just good enough, and that those games had their success based on their strengths in other areas. Not because of the pen and paper style game mechanics, but despite of them. Pen and paper rules system are designed to be a.) played by a group of people, b.) generate randomness by rolling dice, and c.) have all the calculation done mentally in the middle of gameplay. CRPGs, even iso-RPGs are complete different. They are played by a single player, and all the randomization and calculations are done by the computer. Yes, you can play a videogame with pen and paper game mechanics. But very clearly this is not the optimal tool. This is using mechanics that are designed for human ergonomics and the extreme technical limitations of pencils, paper, and dice. Supposedly, the first American President who was known as a passionate golf player said that "Golf is a game where you try to move a ball into a hole, with the help of an implement that is supremely unsuited for the task". Challenges can be fun, and are often a main thing that makes a game engaging in the first place. But I think when designing a rules system for a CRPG, the whole concept of dice rolls and the calculations being simple enough to quickly done in your head by an average player really should be discarded. We're playing with a computer. Let's use the computer's capabilities.

The Core Mechanic

With that being said, my background is still as a pen and paper roleplaying game designer. I am creating a new rules system from that basis and not coming up with something completely unique and original from nothing. Also, even if players don't have to be able to calculate the math of the game, they still want to understand what the computer is doing. So this is all still an isometric CRPG rules system that I think shouldn't be too difficult to grasp for most people familiar with these games.

At it's core, the rules are a skill-based system. That means the stats of characters are primarily defined by a set of skills. There are no character classes, there are no class levels. And in case of this game, there are no experience points either. (A game mechanic originally created to track advancement in class levels.) And in this system, almost every action that characters can perform that has an uncertainty of success or failure is covered by a skill. Shooting an arrow at an enemy is a skill. Casting a spell is a skill.

Each skill has a rank from 1 to 100. This is inspired by some pen and paper rules system that use two ten-sided dice to generate numbers from 1 to 100. With a computer, this could just as well be a range from 1 to 400, 1 to 1,000, or 1 to 100,000. But I feel displaying skill ranks as a percentage value for the chance of success is a very good way to make the character stats human-readable.

When a character performs an action that has an element of uncertainty about success or failure, the computer makes a skill check. It takes the rank of the skill, plus the value of an associated attribute, plus modifiers imposed by equipment, plus modifiers imposed by environmental conditions, plus a difficulty modifier of the target. The resulting value is percentage chance for the action to be a success. If the resulting value is 100 or greater, he chance for success is treated as 99%.

The skill rank and the attribute value are always positive numbers, but modifiers from equipment and environment conditions can be either positive or negative.

Character Advancement

Characters don't have levels and do not gain any experience points. Instead, characters advance by improving individual skills by using them. In systems like this, there are three main things that skills can advance. Any time you use a skill. Any time you succeed at a skill. And any time you fail at a skill.

Increasing a skill any time you have a success seems the most obvious choice, but I think it's the least interesting. It means it will take forever for a weak character to become decent in a skill, but then it will just keep getting up faster and faster. That's a bad mechanic. (Looking at you, Morrowind.) Increasing a skill any time it's used is better in that regard, and an option I am keeping on the table.

But for the first prototype of the game, I'm actually strongly favoring skill increases on failure. It has a number of very intriguing effects. First, a really bad character will become decent at a skill fairly quickly. You get a lot of failed attempts, so you get a lot of advancement. This makes it feasible to make a character become competent at a new task later in the game. Second, it makes good characters advance further in a skill increasingly slow. This makes it unlikely or at least very hard for a character to cap out any skills at their maximum. But the third effect is my favorite: If characters become stronger and more competent by failure, players have a strong incentive to keep playing after their parties were soundly beaten rather than reloading the last quicksave and trying again until they get the optimal outcome. When you reload after a fight that went poorly, you are losing all the skill increases that your characters got. This of course requires a game structure in which combat can end in more than just victory or a Game Over, and in which defeated characters are not automatically dead. But that's a topic to cover later.

Having skill ranks from 1 to 100, and increasing by 1 rank every time a character fails a skill check would mean each skill is maxed out after 99 failures at the most, and for skills like close combat or sorcery, that just isn't enough for a videogame of decent length. So instead of a skill increasing automatically on a failure, they actually only get a chance to increase. That chance for the skill to increase is 100% minus the current skill rank. If your skill is currently at rank 10, you have a 90% chance that your skill will increase on a failure. At rank 68, the chance is 32%. This means that even if enemies and obstacles later in the game have higher difficulty modifiers, and strong characters still keep failing skills somewhat regularly, further skill increases become very rare at the highest skill ranks.


Though I said that the game system is highly skills-based, characters still have four main attributes. Strength, Agility, Cunning, and Charisma. These attributes have a value of 1 to 30, and their value is added to the skill rank when making a skill check. They basically give additional skill ranks to each skill when making skill checks. But very importantly, they don't get added for the probability to increase a skill by 1 rank on a failed skill check. While a character with 25 in an attribute and 5 in a skill, and another character with 10 in an attribute and 20 in a skill have the same base success chance of 30% for a skill check, the first character has a 95% to increase the skill on a failed check, while the second character only has an 80% chance. And since attributes are fixed values that don't change throughout the game, this effect on skill advancement will persist throughout the whole game. A character with a low stat in the associated attribute can still gain a very high skill rank if the skill is used (and failed) often enough. But for two characters who get the same amount of skill uses and skill increases, the one with the higher stat in the associated attribute will always be at an advantage.


Full disclosure here, this approach to combat is directly inspired the Year Zero RPG system used in the pen and paper games Mutant, Coriolis, and Alien. It's so much better than simply having characters hit each other until they are dead at 0 hit point.

Characters don't have hit points that are counted down. Instead they have exhaustion that is counted up. When an enemy lands a regular hit in combat, the character that got hit gains a number of points of exhaustion. As exhaustion points go up, the character's skills go down, including the Defense skill. Increasing the risk of taking further hits.

Actual injuries take the form of critical hits. A critical hit goes through a character's armor and causes a serious wound. Each such wound applies a serious penalty to one or more skills. An injured leg reduces speed and defense. An injure right arm reduces hit chance and damage. An injured head applies permanent exhaustion points that don't go away through regular rest.

Here things start to get more vague and I think this is something that has to be explored through prototyping and seeing what works and what doesn't. But at some point, exhaustion and critical hits will knock out a character. There has to be a chance that a disabled character will die, but also a good chance that there will be plenty of time for the remaining party members to carry disabled characters to a healer. Or a character with a very high healing skill to treat the injuries right there. Once characters have received treatment for their injuries, they are no longer at risk of dying, but will require extended rest to recover from their wounds. Depending on the severity of the injuries, this might require leaving the character in a healer's care for a few weeks. But characters who are at least able to walk can be again added to the active party and participate in combat with their current impairments. Though of course the healing of the remaining injuries will be much slower on adventures than when staying in a healer's care.

I am really excited about this combat system because I've always been hugely fascinated by the idea of dragging disabled allies out of danger and then having to completely throw out the plans for the current adventure while trying to get a dying character to a healer fast enough. Which is something that classical iso-RPGs just never did. Character out of hit points? You're dead. Or you automatically wake up at the end of the fight and everything's fine. The one game that I played where you have to recover fallen party members after a fight (that you might have had to retreat from) before they bleed out, and then carry them to a bed where they can slowly recover is Kenshi. And it's absolutely glorious. Dungeons & Dragons made magical healing so accessible fairly early on in it's history that this aspect of adventuring disappeared completely, but when I first saw it in the Year Zero system reading the rules for Coriolis, it immediately blew my mind. This is so cool, and I really want to make this a big part of my game mechanics.


I don't really have a good draft for a magic system yet. But I do have a few ideas that I want to pursue and that integrate it into the skills and combat systems.

As everything else, Sorcery is a skill. But taking an inspiration from Bloodborne's Insight and Frenzy mechanics, I really like the idea that a higher Sorcery skill reduces a character's resistance to magic effects. The more control you have over magic, the more vulnerable you become to it.

Secondly, I think instead of using mana points or anything like that, casting spells should also increase exhaustion. Just like being hit by attacks in combat. And as with all skills, exhaustion lowers your Sorcery skill to cast further spells. How that works out in practice really has to be tried out in prototyping.

And that's the current state of my plans for the rules mechanics of my game. Still fairly vague in many places, and balancing everything to make for a fun game will largely be a matter of trial and error. So things will probably chance quite a lot over time, but as an initial road map, I think this is a really cool start.