The Peril System: An (Overloaded) Encounter Die as the Core Mechanic
In this post I'm going to detail the system that I've been using to run my DIY/OSR games for a bit now, and hopefully in doing so I'll solidify some of the more nebulous aspects of it for myself. Before I get into that however, I want to point to my main influences on developing this system. The idea of the overloaded encounter die, particularly the one detailed in Meandering Banter's post, as well as Necropraxis' Hazard System have been central to the development of this whole thing. If you're not familiar, I'll all but demand you go follow those links, (primarily because you'll enjoy them and your games will benefit but also because I'm lazy and don't want to explain everything), but essentially the overloaded encounter die is an encounter die with results keyed to every number, so instead of just "encounter on a roll of one", a roll of three might be "torch burns out" or something along those lines.
Anyone reading these rules should be well aware that I believe firmly the "Rulings Over Rules" philosophy and as such am just providing the framework that I myself use to run games. There is a great deal of meat missing from these bones, and I suggest you use whatever methods you like to Frankenstein yourself a monstrous corpse that pleases you (that metaphor got a bit out of hand).
There is no upper limit to the number of Peril Dice a player can roll. The GM also has no obligation to reveal the source of the danger that is forcing the player to roll more dice, though of course they can if they so choose.
Modifying Peril Dice
Relevant character Traits can add or subtract to the Peril Die roll, as can tools, equipment, and other advantages or disadvantages created through clever planning or chance.
A slight advantage should result in a +1 to the roll, a significant advantage with a +2, and an overwhelming advantage with a +3 or higher, with the same being true inversely for disadvantages.
Something to keep in mind is whereas a +1 bonus on a d20 roll constitutes a 5% increase in the likeliness of success, a +1 on a d6 roll constitutes a 16.67% increase. Roughly, I've found that giving a +1 bonus in the Peril System for every +4 or under bonus that would be given in a standard d20 game works pretty well with some common sense exceptions applied.
Skills and other relevant training your character might possess do not add to the Peril Die roll, but instead, give you the option of reducing the number of Peril Dice you have to roll. So if you're trained as a thief and trying to pick a lock in a situation where that would call for a roll of 3 Peril Dice: one for the lock itself, one for the trap concealed in the mechanism, and one for the guardsman rushing down the hall towards them, you could choose to roll 2 Peril Dice.
EDIT: After some helpful feedback from reddit, I made the Peril Die reduction from skills optional rather than automatic. This way if you're feeling confident in your abilities you can choose to roll all your Peril Dice, potentially getting high rolls and gleaning benefits, but if you feel you can't risk it you can focus up, dial in, and ignore the surrounding dangers in favor of getting the job done.
The GM has final say as far as which specific Peril Dice can be nullified by your skills.
Increasing your characters skill in a particular field increases the number of Peril Dice that they may ignore when that skill is relevant.
Careful planning and fictional positioning can always nullify relevant Peril Dice as well. There is no limit to the number of Peril Dice that may be avoided in this way.
When someone is attacked, the Defender rolls at least 1 Peril Die for the attack +1 Die for each point of Might the Attacker has, +1 Die for each other relevant dangerous factor. Significantly dangerous or advantageous weaponry or skill on the Attackers side imposes penalties on the Defenders roll, while significant armor, shields, and skill on the Defenders side gives them bonuses.
The Attacker interprets the result of the Peril Dice that they are responsible for making the Defender roll.
For example, if the Defender rolls a 4 (Expiration: loss of a resource) the Attacker could declare that they disarm the Defender. GM has final say over what works and what doesn't.
Though I've handled multiple opponents in different ways depending on circumstance, my most tried and true method is to simply have the Defender roll an additional Peril Die for each Attacker beyond the first, but to only keep track of the penalties inflicted by the weaponry/skill of the first Attacker.
Wounds and Dying
As indicated on the Peril Die key, a roll of 1 in combat indicates that the Defender has received a major, possibly lethal wound.
A roll of 2 indicates a significant wound, and a roll of 3 indicates a minor, temporary or transient wound: bruises, being winded, etc.
A major wound counts as a dangerous factor in all circumstances, forcing the player to roll an additional Peril Die until it is healed.
A significant wound counts as a dangerous factor in some, but not circumstances, depending on the wound, until it is healed.
A minor wound counts as a dangerous factor on the next roll, but no rolls after that.
At 2 major wounds, a character is dead.
You should feel free to adjust the number of major wounds it takes to kill characters to suit your own campaign: I go with 2 for the average character, with 1 for weak characters, 3 for strong ones.
There's a great deal of potential flexibility with character creation in this system: it'd be pretty easy to use the standard D&D stats with a range of -2 to +2 (keyed to a 1d6, 1 = -2, 2 = -1, 3 = 0 etc), and a Whitehack or even GLOG style class system would be really easy to implement as well.
I'm just going to demonstrate the one that I use, which has been serving me pretty well.
Roll a 1d6 3 times. On a 1-2, write down or roll for a negative trait your character has. On a 3-5, write down or roll for a negative and a positive trait, and on a 6, roll or write down a positive trait. Opposite Traits cancel each other out, don't write down either of them. Duplicates increase the serverity of the Trait, write a + or - (depending on if it's positive or negative) next to it for each duplicate. I'd recommend stealing someone else's character trait tables, but if you can't be arsed, here's 2 perfectly serviceable ones.
d6 Negative Traits
d6 Positive Traits
Choose a table of former professions and roll on it, there's a million out there, I promise. Write down the result you get.
Choose an appropriate table of random items for your game and roll on it 3 times. Again, if your GM hasn't made one, someone else has and you can nick it.
You may carry 18 Significant Items: 100 Coins is a significant item, as is a piece of armor or a weapon. You may carry as many insignificant items as your GM will let you get away with.
I fluctuate between letting players carry 18 items and 12 items. Sometimes if I'm feeling particularly fancy I'll let Strong characters carry 18, normal characters carry 12, and Weak characters carry 6.
I've been using this table that Meandering Banter has been working on. The abilities require a bit of tweaking but essentially: any damaging effect results in the one affected rolling a Peril die with a bonus or penalty depending on the severity of the damage: 1 damage = +4. 1d12 = - 4.
Mansel Pointel, the Raucous Expeditioneer
Background: (I used the failed careers from Electric Bastionland)
Items: (I'm using some tables I've assembled hodgepodge from the tables of too many people to remember and thus am declining to share them)
Carved Sages Rod
Obsidian Table With Blasphemous Runes
Abilities: (using the aforementioned table)
Immune to basic undead touch attacks
When I dance, everyone feels like they should be dancing
May use any mundane items as weapons, defenders take -2 on Peril Die rolls, they break on Peril roll of 1 or 6
So what I'm gathering from this mess of info is that Mansel was a canny, careful explorer who occasionally (perhaps more often than occasionally) let drink get the better of him. Not that he wasn't pleasant to be around when drunk: indeed, he was frequently the life of the party, and quite able to hold his own against any who might take issue with his jocular dancing.
However, indulging at base camp led Mansel to get led rather astray, and indeed, he no longer knows where he is. He only knows that he seems to have taken the artifact that his expedition had recovered and that it hasn't had a good effect on his health. His skin has grown more pale and clammy, his eyes more sunken and hollow. He's found he no longer suffers paralysis at the hands of ghouls, which is good, since they seem to seek him, or perhaps the artifact, rabidly...
I personally use Gold for XP. Upon attaining a level, a character may choose to increase the number of major wounds it takes to kill them by 1, increase their Might by 1, or improve the efficacy of one of their abilities. Alternatively, they may store the XP, choosing to spend it when they meet an NPC with an ability they wish to learn: they may then spend the XP to learn the ability.
You could easily use whatever XP system you liked based on what gameplay you want to incentivize and how quickly you want players to level up.
Last Thoughts: Magic, Some Other Stuff
I haven't been letting players start with spells, and I run a class free game. When players do encounter spells, I use Knave spells or Wonder and Wickedness, along with the Last Gasp Grimoire spell disaster tables. Provided you are comfortable with the system, it's pretty easy to make damage/save rulings, and I haven't had any trouble with it. GLOG magic would also work without too much fuss I think. Trying Vancian magic in this system seems like a headache, but you could certainly give it a go.
In any case, this is the system as I run it: obviously incomplete, heavily reliant on the GM to carry the weight of interpretation and ruling, yet also pretty freeing, in my experience, if you're a GM who likes every roll to have fictive weight and likes to improvise unexpected results consistently. I've been using it to run OSR games (using it for Silent Titans currently) and it's worked wonders, though it might scare off some of the more traditional types. I'd love to hear what people think, love it or hate it, and that's all for now!