The average of a die roll is half that die’s size plus 0.5. This is most often used to expedite rolls made during long periods of downtime.
To determine how many hits are scored within a given number of rolls, take the number of dice rolled times the number of sides that hit, and divide that by the total number of sides.
Always round non-whole numbers in whichever direction is worse for the players!
Players receive XP instead of their characters. Players then spend XP on their characters as desired, but cannot advance a given character more than 1 level each month.
Players in Mythic Past campaigns get 3 Hero Points when they embark on an adventure.
A player can spend 1 Hero Point to make a reroll. If a character has less than zero HP, their player can spend all their remaining Hero Points to set their HP to zero.
A player cannot have more than 3 Hero Points at a time.
A player can simultaneously control up to 4 owned characters. Controlled characters are called “active.”
A player starts with 1 owned character “slot.” They “unlock” 1 more slot when they have a character reach 3rd, 5th, 7th, 9th, and 11th levels, for a maximum of 6 slots.
A player can at any point demote an inactive character into a henchman. A character demoted into a henchman retains their level but no longer gains XP.
A henchman can be an active character only if an owned character that is at least 2 levels higher is also active.
In campaigns set in the mythic past, demihuman classes are available.
In campaigns set in the 17th century, demihuman classes are available, but their members are not overly distinct from humans.
In campaigns set in the 19th century, demihumans are nonexistent.
A character with less than zero HP who regains any amount of HP does not regain consciousness until naturally healing at least 1 HP.
When a character gains 1 dot of Languages, they check each language they do not know to determine whether they now know it.
A character can learn a pictographic language in (7 minus N) times (20 minus Intelligence) days, where N is the number of Language dots they have. Pictographic languages can be spoken in any language.
If a character has N points in an ability and N is less than 16, they can be trained by a character with at least N plus 2 points in that ability. After cumulative days of training equal to 20 times (N plus 1), increase that score by 1.
A new player character is 2d6 plus 16 years of age. All characters treat January 1st as their birthday.
If a character has N dots in a skill, and N is great than 3, they can be trained by a Specialist with at least N plus 2 points in that skill. After cumulative years of training equal to N plus 1, add 1 dot to that skill.
All months have 28 days, start on a Sunday, and end on a Saturday.
Winter takes place from November to February. Animals cannot graze during these months. This is what animal feed is for.
A character with an addiction suffers the effects of sleep deprivation for each day they do not indulge.
Spiking a door open takes 10 minutes and costs 1d6 spikes.
Small items of the same kind count as 1 regular item when stacked no higher than your Strength.
If an animal is carrying an item that counts as multiple oversized items, it instead counts as that many items and must be carried in a vehicle.
Ships can carry N times 80 EP, where N is the ship’s cargo capacity.[^1^](#sdfootnote1sym) For simplicity, count oversized items, passengers, and mounts as normal items. Also count the EP of mounts as items. Artillery counts as 1 item per size category. Rafts, canoes, and lifeboats can be carried, each of which count as N times 80 items, where N is that ship’s cargo capacity.
A character adds N minus 1 to the cubic feet of earth they excavate each hour, where N is their dots in the Architecture skill.
A party only gets lost if they are not on a road or surrounded by terrain other than plains. The Referee rolls a random direction for the party to travel in. They travel in that direction for days equal to 7 minus N, where N is the highest Bushcraft dots among party members, or until the terrain changes, they find a road, or they find a settlement or other significant landmark.
The referee checks for a random encounter after each 1 hour of adventuring. There is a 1-in-6 chance of a random encounter. When traveling, add the chance of getting lost for the terrain of the hex.
The Referee adds 1 to the random encounter chance for every 30 feet the party’s speed is lower than 120.
Searching an area reveals everything hidden in that area. Searching an area includes listening to all that area’s exits.
You cannot sleep in the wilderness without a bedroll. You also need a tent if you are in an extreme climate. A successful Bushcraft check lets you sleep a night in the wilderness without a bedroll, or sleep in an extreme climate in only a bedroll.
Sleep deprivation affects how many spells Elves and Magic-Users can memorize. For every minus 1 penalty, treat their spell slots as if they were 1 level lower.
A character who is swimming moves half their speed. A character swimming underwater can hold their breath for rounds equal to their Constitution score. When a character runs out of breath, or they lose any number of HP while holding their breath, they make a save versus Poison against drowning at minus 1 for each such save made since last breathing, or they become unable to move and die after rounds equal to their Constitution score.
While adventuring, a character spends 10 minutes whenever they make a skill check.
An encounter with NPCs is rounded up to the nearest 10 minutes.
A lit lantern can be thrown as lit oil and deals additional damage as if it were a thrown rock.
Thrown holy water that does not break still deals damage as if it were a thrown rock.
The firearms appendix is not used for campaigns set in the Mythic Past.
The firearms appendix is used for campaigns set in the 17th century. Flintlock is the default mechanism and all firearms are considered rifled; however, their prices are as shown in the table on page 157 of Rules and Magic. Muskets do not need forks. For simplicity, ignore the increased armor prices dictated by the appendix.
The firearms appendix is used for campaigns set in the 19th century. Pistols are revolvers, arquebus are shotguns, and muskets are rifles. Powder horns are no longer needed, but shot bags are. 6 shots are permitted before reloading for 3 rounds (1 for Fighters).
Delivering freight costs the amount shown in Rules and Magic, plus 5% of the freight’s total value each day by land and each week by ship.
Creating a wooden holy symbol while in the wilderness takes 8 hours of crafting and spending 1 first-level spell slot.
Drinking a potion takes 1 round, but drinking only 1d20% can be done as part of movement, though it provides a proportionately diluted effect.
A private charter costs the amount shown in Rules and Magic, per person, per day.
Standard rations must be cooked for at least 10 minutes before eating and spoil after 1 week.
A character with a scroll case can retrieve scrolls as desired. A character without a scroll case must spend 1 round to retrieve a scroll, plus 1 round per EP after the first.
Chariots and carts have 1 axle. Coaches and wagons have 2 axles.
Chariots and carts cannot enter difficult terrain. Coaches and wagons cannot leave roads.
If a person has their own waterskin, they are assumed to have enough water to drink. If 10 people have a barrel of water, they are assumed to have enough water to drink.
A character spending bless points on a percentile roll adjusts that roll by 10% per point spent.
If a character casts bless on another character, if that character is under the effects of bless originating from another caster of the same alignment, increase the existing point balance to a maximum of N plus 6, where N is the originating caster’s level.
A Magic-User can prepare read magic without a spell book, but it is the only spell they can prepare that day.
A bonus to the caster’s domination roll requires both sacrifices and a thaumaturgic circle. Multiply the amount of HD and SP required by 10.
Investment growth counts as XP gained that are distributed equally among all players within its owning group regardless of their presence or contributions.
A character can work a given investment to decrease that investment’s bankruptcy change for this year by 0.10% for every cumulative 28 days worked.
Creating a settlement is a wild investment worth 10 times the settlement’s daily transaction limit that must remain wild for 2 times N years, where N is that settlement’s size.
A settlement’s size is 1 for a village, 2 for a town, 3 for a city, and 4 for a metro.
A settlement can handle total daily transactions equal to $100 times (N times 10), where N is that settlement’s size. Add 10% of the total value of investments in a settlement to the total daily transactions it can handle.
Spending starting money in a settlement never counts towards its daily transactions.
Give each player 1 Hero Point when they finish a combat encounter and when they find a treasure hoard.
Named NPCs in the Mythic Past who have titles get 1 Hero Point per character, per encounter.
The value of a given treasure is worth money equal to the cumulative XP a Fighter of the adventure’s intended level needs to reach the next level. This amount is adjusted by 1d100% minus 50%.
For example, if an adventure is intended for 5th-level characters, a given treasure is worth $16,000 to $48,000.
Note that extracting a treasure should never be easy, and selling it should never be straightforward. Often, a buyer will negotiate for another 1d100% minus 50% price modification, up to the transaction limit of a settlement. A character can find 1 buyer per treasure per day.
1Assume 20 coins weigh 1 pound (per Moldvay B/X). 1 ton is 2,000 pounds. 100 coins count as 1 item for encumbrance. Thus, 1 ton is equal to 400 items. Mounts carry 5 items per 1 EP.