What is Labyrinths and Outlands? The Nat40 System
LNO, as one might guess, is to be a TTRPG that follows in the same general vein of Dungeons and Dragons, Pathfinder, Dungeon Crawl Classics, and countless others, but also taking inspiration from a great dearth of video games and other media. A cynic might call it a heartbreaker, and it certainly is accurate to say that LNO is precisely the kind of game that I personally would want to play, but ultimately its the culmination of a great many years of playing and thinking about how games should be.
To pitch the game in a nutshell, it is intended to be a sandbox forward game that focuses on exploration, crafting, and high octane war-gaming that provides for smooth, fast paced combat that can scale from the 1v1 Duel to massive battles with hundreds of thousands of combatants with minimal changes necessary to the gameplay.
Technically speaking, at this point the project is around 12 years old, as I had the original creative sparks for what would blossom into LNO back in 2011 when I thought about how I might have done Skyrim better, but the actual bulk of the work has been done in the last 6 months or so in the wake of the OGL debacle with Wizards of the Coast. I had intended on starting LNO at some point prior to this, but I was unsure of whether or not I was going to base it around a hack of d20 Modern or if I was going to try for a bespoke system. The OGL debacle made that decision easy, and within about a day once it became clear that what WOTC was trying to do was, in fact, what they were trying to do, I got to work.
What resulted out of that essential honeymoon period of game design is a system that I call Nat40. At its core is a three-tiered resolution system. For Combat, 2d20 is used for resolution. For Skill resolution, 2d10, and attributes 1d10.
The Skill and Attribute system takes a great deal of inspiration from the Runequest lineage that included The Elder Scrolls video games, and it will be very familiar to players of those games. Each Attribute has a baseline value that is determined by a 5d6 Roll DTL.
With 28 Skills spread across 7 different Attributes, leveling is achieved by, well, leveling your skills through usage. At this time, you gain skill points (up to a maximum of 30) whenever your roll your 2d10 and roll either doubles, a Nat 2, or a Nat 20. When you take your Level Up, you have the option to rearrange your newly earned skill points to other skills, so it benefits you to not be hesitant to use a relevant skill to try and resolve something (re: Skill Challenges), even if its not one you need for your character. Once you arrange your skill points, they become permanent.
Every 10 skill points in any skill will level your character (giving you Class levels), and for each Attribute, the cumulative total of your skill points in that Attribute determine your Attributes final value. If for whatever reason a Skill cannot cover a needed resolution, you can opt to make a Talent Check (1d10) against one of your Attributes. Whatever you roll, you take that number and divide your Attribute by it to determine your Talent Rating, rounded down (which is then compared to the Talent DC of whatever it is). For instance, if your Strength is at 120, and you roll a 7, your resulting Talent Rating will be 17. Obviously, rolling lower is ideal, where elsewhere rolling higher is ideal. (This is something I've been unsure of as its a bit, inelegant, but I have not really found a better way forward as of yet)
Unlike in DND and many other TTRPGs, Attributes in LNO are strictly passive. They have no specific modifiers that they provide, and the Talent Check is the only means to use your Attributes to directly resolve something in-game. Attribute modifiers are instead consolidated into the Energy System, which not only provides for a universal resource system for characters, but also provides 3 Modifiers to work with, similar in structure to the Fort/Will/Reflex of DCC and others.
Composure is the first of these Energies, and is the effective equivalent of Hit Points in other systems. Composure is derived from the combination of your character's Endurance and Willpower attributes, which correlates to the fiction of Composure representing the characters physical and mental ability to defend themselves. (more on this with Combat)
Mana is the second, and as one might guess is for the use of Magic. It is derived from the combination of either Intelligence or Wisdom, and your character's Willpower.
Stamina is the last, and is again self-explanitory. It is derived from the combination of either Strength or Dexterity, and the character's Endurance.
If the character has had all of the related attributes for one of these Energies maxed (which is a minimum of 120), the character receives a 1.5x bonus to their totals for that Energy. This encourages having a diverse skill set, and the spread of the skills throughout the attributes (particularly for Endurance and Willpower) is set such that the skills pursued are mostly still going to be thematic to such characters, bridging the gap between the optimizer and the roleplayer as to what would be preferable to pursue.
For each of these energies, a modifier is derived from each and these modifiers serve a number of purposes. Their primary purpose is for saving throws, and I have begun to utilize a relatively unique nomenclature for this. For example, an Ogre that uses their “Wreckless Overrun” ability might induce a +10 Stamina save. What this indicates is that in order to resist this ability, you have to make a saving throw that is equal to the Ogre's Stamina Modifier + 10, and you would simply roll 2d10 and add your own Stamina modifier to attempt the resist. This same idea carries through for all saving throws, and any your character induces would likewise be based on your Energy Modifier plus whatever +X the ability grants you.
Their secondary purpose is for the streamlined tracking of your Energies themselves, specifically your Mana and Stamina. For these two Energies, your modifier represents your standard drain rate for any action or ability you use. IE, if your Mana Modifier is +6, then any basic spell you cast costs 6 Mana every time. Some of these abilities will come with modifiers with this, asking you to double, or even halve, or some other multiplication or division. The idea is that tracking these will be easy, as you can simply make tick marks to notate how much Energy you have consumed, and you can, ahead of time, divide your Modifier into your Energy to determine the maximum Ticks you can make.
Composure does not work this way, though not without trying. We playtested it that way but not only would it require some weird and rather esoteric ways of doing things like weapons and armor, but it ultimately just didn't feel very great.
The Energy Modifiers also stand in for what Attribute modifiers would provide in other systems, giving additional boosts to Skill Checks, Combat checks, and other systems such as Crafting.
The Combat System, from which the Nat40 Name is derived, is as mentioned 2d20 based. However, it is more accurate to say it is a 2x1d20 system. Combat is based on an Act/React structure, and at the beginning of a combat round, all characters roll 2d20, and they can assign one of these die to either their Act or React, or alternatively they can opt to double down and put the cumulative total into just one, precluding the ability to use the other for that round. The resulting value, after modifiers are added, represent your Act and React Ratings, which are then used to determine the effectiveness of nearly everything you do during the combat round. Combat itself is typically initiated with an initiative roll, and like your typical DND game goes in simple turn order.
Your Act, as one might guess, takes place on your character's turn and covers your character's offensive Actions during that turn. This will mostly be attacks, but also includes one Skill Action (taken separately from your Attacks), which is rolled separately using 2d10.
Your React, in comparison, takes place primarily in reaction to an attack, either against yourself or an ally, during which you'd use various Defensive abilities, for which there is a wide variety of options ranging from your basic blocks and parries, but also to various Defensive Spell variants (IE, opting to use your held Fireball to defend yourself instead of attack something) and different class abilities.
However, your Reaction is also your principle currency for a number of different class abilities that can have some widespread affects on the course of the battle. For example, the Barbarian's Yawp! ability is one that uses up the character's reaction, trading defense for the ability to yell so loudly at a mage that their spells peter out and go poof, and at higher levels, yell so loudly and forcibly that puny town guards have their armor and weapons torn to shreds by the sheer power of your voice. These kinds of abilities are not always restricted, and can be used at any time, including during your Act, if you wish.
During either instance, you have free use of your Movement, which unlike many other games is actually rolled for rather than fixed. Your movement keys off of your 2d20 roll + your Stamina and Athletics Modifiers. However, using up all of your movement does preclude you from being able to defend your allies form attacks if your Defensive ability requires you to be within a certain range of the attack, so it is wise to allow yourself some movement to stay mobile throughout the round.
As noted, your Act/React ratings determines the effectiveness of the actions you take during them. If you roll a Nat20 and assign that die to your Act, then all of your subsequent attacks will be made as if you rolled a Nat20 for every single one (and thus giving you a Critical Hit on each). Likewise for defense, with a Nat20 providing you the ability to “Critically Defend”, allowing you to double your Armor Rating. Thus, the value of rolling a Nat40 is pretty substantive, as it gives you a great deal of power on the battlefield.
However, Attacking and Defending isn't quite as simple as that. Firstly, in order to inflict full damage, any attack must still exceed the needed “Accuracy Class” (AC), which is a combination of the target's Armor Rating (AR) and their React Rating, if they reacted in defense. If your attack does not exceed this value, and they have not reacted defensively, you will only inflict half of whatever damage value you roll. If they have reacted defensively, your damage will be further penalized by the targets Armor Rating, which when added together with their React rating can provide substantive damage reduction. Naturally, this system works the same way for yourself when you are attacked. If you can, it is wise to defend yourself, as that is the best way to mitigate, if not eliminate, any incoming damage.
Additional to your Act and React Ratings, you also have available to you a Passive React Rating, which forms the core of the Stealth mechanics for LNO. This rating is the cumulative addition of your Perception, Athletics, and Composure modifiers, and can reach a maximum of +45. Your Passive React rating serves the primary purpose of determining how well your character is able to react to things such as sneak attacks, traps, and other dangerous things that you need to deal with.
Whenever a perceived trap or creature attempts an attack against you, and Combat has not already begun by rolling initiative, they will roll 1d20 to determine their Act rating for the attack, and if this value exceeds your Passive React Rating, then they will gain the benefits of a Surprise Round against you, which grants them the ability to use their full Act as they see fit, and they may choose to roll and utilize a React if they wish.
If the attack does not exceed your passive React, then you receive the ability to take a full Reaction, rolling 1d20 and adding your Passive React Rating to it for effectiveness.
As strong as this can be, however, this changes when a creature (or an undiscovered trap) is using stealth to avoid detection. Stealth checks themselves are principally rolled against the environment (IE, you have a harder time being stealthy on a sun-lit road than you do in a bush in the dark), which then trigger perception checks if failed. But, if a creature (or trap) is successfully hidden when attempting the attack, they will receive a bonus to their Act rating equal to their Stealth Check – the Stealth DC, up to a maximum of +10. Any excess Stealth beyond +10, instead converts to a lowered Critical Hit chance, again at a 1:1 rate.
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Now, this big long diatribe is just the core of the system. The relatively basic bits and bobs that, even without all of the actual content I have written since, is quite fun and most importantly
feels really fun to play. Combat itself while it can be a bit weird to grok at first, especially coming from other TTRPGs, but it has consistently proven to be quite fast paced and intuitive once you do, as the ebb and flow of attacking and defending seeks to mimic, as much as a TTRPG can, the cinematic feel of fighting, but without abandoning the more crunch tactical considerations that are more traditional to DND, and it seems to accomplish this pretty well.
Indeed, part of the philosophy here has been to find that same middle ground between the cinematic and the pure crunch. The use of an Act Rating for instance to cover all attacks made during a turn, is actually a measure taken to provide a middle ground between the usual (rolling for each attack over and over) and the usual alternative of just rolling for Damage and skipping the additional roll. Likewise this is why there is both an AC and Damage Reduction, as while cumulatively doing both is a bit more “complex” (as loaded as I find that word) than just doing one or the other, I've found that this just feels more right, if that makes sense, but is still relatively simple to use.
But, it also has benefits in that it keeps attentions up during combat even if it takes a while to work through a round. The opportunity to use your React is potent, and when combined with classes that enable a more offensive use of your React (Like the mentioned Barbarian ability Yawp!), there's a lot of chances for characters to work together to really dominate the battlefield.
And the best part, in regards to combat, is that it does scale. The same basic structure works whether its a duel or a massive LOTR style army vs army battle, which funnily enough wasn't actually intended. I didn't set out to make this a more deliberate wargame, but it has lent itself to that, so I'm going to be leaning into it (and I'm quite excited by my Siege mechanics, to speak vaguely

)
While I haven't spoken much of the Skill system, which is the really meaty part of the game, thats mostly because I'm still working through developing each skill. Much unlike DND and its ilk, I am doing my damnedest to avoid the simplistic binary Skills of yesteryear, and I'm developing a great deal of different features, mechanics, etc that can be activated through Skill usage. The best example of what that will look like is in the Crafting Mechanics, for which I developed a core mechanic to cover the various Crafting skills called 7 Dice, which I have actually detailed in another topic elsewhere on the forum, but I'll leave that description up to another post later on.
Skills in LNO, being the sole source of progression, obviously have to be a lot more than the things we see in DND, and this incidentally provides the perfect reason to emphasize Exploration as a core part of the game, as the best way to use your skills more and get those Skill Points, is to just get out into the world and do stuff, and that was the next biggest thing that I focused on early on, so that will have to be another post to cover as well.