OSE is a great revival of old D&D, and the 2026 update is terrific, but the desire to keep it compatible with old-school D&D adventure modules means it still suffers from many of the same issues the old game had.

The primary issues, as I see them, is that players of martial characters and rogue characters don’t get to make choices when they level like casters do, nor do they get to make tactical choices during combat like casters do. Now, too many tactical choices (together with too many actions) are was make modern D&D (and Pathfinder and Draw Steel…) very slow during combat, so caution must be exercised. But there are ways to fix OSE without turning it into a modern game.

Basics: Advanced

In general, use the advanced optional rules.

Character Creation

STR	Modifier	Max Lift (lbs)
1-3	-3	5, 15, 30
4-5	-2	45, 60
6-8	-1	75, 90, 110
9-12	—	130, 150, 170, 190
13-15	+1	210, 230, 250
16-17	+2	270, 300
18	+3	320

There’s a standard ability score modifier, seen at right. And, personally, I prefer generous ability score generation, like 2d6+6.

Strength

Opening stuck doors, etc. should be a matter of a specific Max Lift score. A prybar doubles your Max Lift; a helper (no more than one) can add 50% of their Max Lift.

Classes & Levels

Single-class characters start at 2nd level; use average hit points rounded up. If you allow multi-classing (“hybrid classes”), those characters start at 1/1 but with hp from both classes. Characters only apply their CON hp bonus at odd levels.

A mage/rogue would get 2.5 from mage and 3.5 from rogue, for 6 hp, but future hp is 3 hp per level—an average of the two.

Level	Bard/Rog Cler/Dru	Barb/Ftr/ Knt/Pal/Ran	Ill/MU
1	0	0	0
2	0	1	0
3	1	2	0
4	1	2	1
5	2	3	1
6	2	3	1
7	3	4	2
8	3	4	2
9	4	5	2
10	4	5	3
11	4	6	3
12	5	6	3
13	5	7	4
14	5	7	4

Attack Bonuses

Attack bonuses are smoothed out and reduced at high level, to account for certain new features.

Spellcasters

Import the idea of cantrips from 5e: zero-level spells that can be cast each round.

Arcane (Magic-user & Illusionist)

Give arcane spellcasters these cantrips:

• Prestidigitation (per 5e)
• Candlelight (produce a candle-like flame on your finger as long as you concentrate)
• Magic Dart (one shot for 1d4+1 damage; roll to hit; blocked counts as a hit)

Additionally…

• In place of mundane spell components, you carry a custom-made staff, wand, or other arcane focus. Without it, you can only cast cantrips.
• You can swap a spell you’ve memorized with another you know of the same level, but you suffer a minor wild magic effect.
• You always have Detect Magic memorized and can cast it a number of times per day equal to your level. You can’t swap it for a different spell.
• Spell changes:
  • Fire Ball does 4d6 damage (not 1d6 per level, but lightning bolt still does).
  • Sleep creates a normal sleep, so sleepers awaken with any normal noise or movement—meaning only those with move silently can attempt executions.
  • Identify basically gives full knowledge of a magic item (except a cursed item).
  • There’s no need for Read Magic. Spellcasters can just read magical writing and spellbooks because they know the language of magic.
  • Light only has an area of effect in a location and can’t be cast on an object.

Divine (Cleric & Druid)

Give divine spellcasters these cantrips:

• Thaumaturgy (per 5e)
• Candlelight (produce a candle-like flame on your finger as long as you concentrate)
• Guidance (per 5e)

Additionally…

• In place of mundane spell components, you carry a holy symbol. Without it, you can only cast cantrips.
• You can swap a spell you’ve memorized with another you know of the same level by spending 10 minutes praying.
• You always have Light memorized and can cast it a number of times per day equal to your level. You can’t swap it for a different spell. Light only has an area of effect in a location and can’t be cast on an object.

Tactical Bonus: You get +1d3 you can add (each round of combat) to your attack, damage, armor class, or the AC of an ally within 5 feet. For missile weapons, you can apply it only to your attack. Clerics and druids only; mages don’t get a tactical bonus.

Martial Classes

Fighter, barbarian, ranger, knight, and paladin are all martial classes. They get extra features.

At 1st level, barbarian, fighter, and ranger choose one of the following features:

• animal friendship: Livestock, pets, and even guard dogs are automatically amiable if you’re friendly. You can make a pet of a small animal (weasel, fox, squirrel, raven…); it hides during combat. You get +2 on reaction rolls with all creatures of beast intelligence.
• climb sheer surfaces: (as a rogue)
• contacts: In any city or in a town near your hometown, check difficulty 10 using CHA to make a new friend or know someone who can help; recover for a friendly rival; natural 1: an enemy. You get +2 on reaction rolls with humans and demi-humans.
• lucky: Once per session, you can reroll a d20 roll, including advantage/disadvantage.
• rope master: You are exceptionally good at knots and hitches, securing loads and tents, and other uses of rope. You can carry 50% more gear before being encumbered and can use ropes to help secure (as a spike) or open (as a pry bar) stuck doors etc.

Tactical Bonus: (all martials) You get +1d3 you can add (once each round of combat) to your attack, damage, armor class, or the AC of an ally within 5 feet. For missile weapons, you can apply it only to your attack.

Martial Prowess: (all martials) At 5th level, boost your damage die. 1 becomes d3, which becomes d4, then d6, d8, d10, d12, and d12+1.

Monster Lore: (fighter, barbarian, and ranger) Make a successful check with intelligence to identify a never-before-seen creature from old warriors’ tales (per DM) and recall a special ability or vulnerability it has. Fail but roll a successful recovery: you know little more than its common name. Difficulty is 8 plus its hit dice. Certain creatures (goblins, trolls, dragons, etc.) are well known. Bonuses: +1 at 5th level, +2 at 9th, +3 at 13th.

Chivalric Lore: (knight and paladin) Make a successful check with intelligence to identify a magical weapon, armor, shield, etc. (difficulty 15) by recalling legends of famous knights and orders of knighthood. You can also identify coats of arms (difficulty 10) and have knowledge of noble families (difficulty 8), ruling nobles (difficulty 12), and other nobles (difficulty 15). Bonuses: +1 at 5th level, +2 at 9th, +3 at 13th.

Magic Resistance: (barbarian) You get +3 on saves vs magic you fear too much to use (per fear of magic). As you come to use it (your choice at each level), this falls to +1.

Battle Cry: (fighter and barbarian) At 4th level, once per encounter immediately before an attack, you can shout a battlecry that gives you advantage on that attack.

Multiple Attack: (all martials) At 5th level, you can make an extra attack (melee or missile) once per encounter. At 9th, you can do this twice per encounter. At 13th, you can do this every round.

Combat Dominance: (all martials) Against inferior creatures (see the table), you gain one or two extra melee attacks per round and treat any hit as a kill. If weaponless, this is a knockout. Creatures immune to precision damage take normal damage.

+1 att	+2 att	HD	Example Creatures
2	4	less than 1	kobold (½), goblin (1-1)
3	6	1	peasant (1), orc (1), wolf (1)
4	8	2	hobgoblin (1+1), zombie (2)
6	12	3	lizardfolk (2+1), deep one (3)
8		4	bugbear (3+1), gargoyle (4)
10		5	ogre (4+1), owlbear (5)
12		6	mummy (5+1), minotaur (6)
14		7	troll (6+6), manticore (7)

At 4th, 8th, and 12th level, all martial characters can choose one feature they don’t already have:

• archery (see below)
• defiant spirit (+2 to saves vs magic; cut duration of unwanted magical effects in half)
• grand charger (see below)
• nerves of steel (see below)
• sense unseen (detect invisible within 20 feet; check 12 with INT from 20 to 80 feet)
• ability increase (+1 to any two ability scores, subject to ancestral maximums)

Archery: Instead of making two bow attacks in a round, you can aim carefully and get advantage on a single attack; any hit with this attack is an automatic critical hit. Also, you get combat dominance with a bow, but with no additional attacks.

Grand Charger: You can go on a quest to find a fantasy mount, such as a griffon, hippogriff, winged horse, or giant lizard, panther, or wolf. Spend one week bonding. The creature will generally behave as a well-trained horse or dog (including fighting) and can manage for itself when not needed. You can sense one another at 1 mile in open ground. This is a special bond, and if the creature is killed, you will mourn for a month but may then quest for another.

Nerves of Steel: You are immune to normal fear and have advantage on magical fear saves and +2 on saves against mind control. You also get +2 to charisma checks with humans and demi-humans. Allied martial characters of lower level tend to follow your advice, especially in urgent situations. You also don’t get disadvantage to rolls from being injured.

Rogue Class

Rather than acrobats, assassins, and thieves, there is one class called “rogue”.

Tactical Bonus: You get +1d3 you can add (each round of combat) to your attack, damage, or armor class. For missile weapons, you can apply it only to your attack. It doesn’t apply to backstab attempts.

At level 1, you can choose one of the following:

• animal friendship: (as martials)
• contacts: (as martials)
• rope master: (as martials)
• lucky: (as martials)

Rogues have the basic features of thieves but may choose any six of these skills:

• appraise valuables (see below)
• backstab (see below)
• clever (+3 on searches)
• climb sheer surfaces
• dagger-fighting (see below)
• evasion (see below)
• find/remove treasure traps
• open locks
• pick pockets (includes a sleight-of-hand ability)
• roof-running (see below)
• spycraft (see below)
• stealth (takes the place of hide in shadows and move silently; uses MS)

At 4th, 7th, 10th, and 13th levels, the rogue may choose the read languages/scroll use skill or any one of the other skills above.

Appraise valuables: You can recognize the quality of goods and estimate their value up to things worth 500 gp times your level. If you fail or it’s above your level-value, you have no idea; if you succeed at recovery, you can give a vague guess. Typical difficulty 10, using intelligence.

Backstab: When attacking an unaware opponent from behind or otherwise undetected (invisible, etc.) with a one-handed weapon, you get advantage on the attack; a hit is an automatic critical hit (max damage plus normal) and you add your level as damage. If it’s done with a dagger and a natural 4 is rolled for damage, the opponent must save vs death or be reduced to zero hp. The opponent must be a normal humanoid of similar size (not undead, construct, giant, etc.).

Dagger-fighting: You can throw in combat (as well as juggle) knives, daggers, and 1-handed axes and get combat dominance (as martials) with them. If you use one in each hand, you can use your maneuver to attack against the same opponent (but backstab is merely +1, not two attacks). Without this skill, a character can’t throw such weapons in combat.

Evasion: Once per encounter, when you’re hit in melee but before you know the damage, you can evade the blow. You end up several feet away (random square around you and the opponent.) At 5th level, twice per encounter; at 9th three times; at 13th four times.

Roof-running: Combines tightrope walking, jumping, falling, tumbling attack, and tumbling for entertainment. You can cross roofs and catch hand-holds as parkour; uses CS skill column; on a failed check, you come down with 1d6+1 damage; recover for 1d4 damage.

Spycraft: Combines disguise, forgery, vocal mimicry, hear noise (includes identifying the source), and encryption/decryption. Check 12 to get the gist of any document written in any language of your realm, recover to get just the subject. Use HS skill column to get a secret out of an NPC during a discussion; beat your target by 50, and they don’t even realize it.

Bards

At 1st level, bards can choose any three of the following skills. At 5th, 9th, and 13th, they can choose another.

• appraise valuables (see above)
• climb sheer surfaces
• dagger-fighting (see above)
• evasion
• find/remove treasure traps
• roof-running (see above)
• spycraft (see above)
• stealth (takes the place of hide in shadows and move silently and uses MS)

Tactical Bonus: You get +1d3 you can add (each round of combat) to your attack, damage, or armor class. For missile weapons, you can apply it only to your attack. It doesn’t apply to backstab attempts.

Skills

There are certain skills that anyone in the society has: etiquette, festival dances, basic animal handling and horse-riding, general knowledge of agriculture and religion, camping, wrestling, etc. There are others, below, that anyone can attempt. The GM decides on the difficulty target. In many cases, failing a check still allows you to roll again (recovery) for a partial or qualified success.

Climbing (DEX)

While anyone can climb a tree with low branches, you can shinny up a tree as well as climb fences, ropes, steep slopes, etc. Check 10 with DEX to climb (non-sheer) stone walls and cliff faces. Roll recovery to fail without injury. Fail both and you fall for some injury from half the height you were climbing for (that is, 10 feet, if you’re climbing a 20-foot wall).

Jumping (DEX)

With a couple of steps, you can jump forward a distance equal to your height. With a run up, you can add 2d3 feet if unencumbered, 1d3 feet if lightly encumbered. If you fall short by 3 feet or less, make a DEX check to catch a handhold.

Persuasion (CHA)

You try to be persuasive by laying out the facts and appealing to fairness and/or just bluffing and making things up (deception) or by making threats (intimidation). Make your basic argument; if the GM agrees that it’s reasonable, make the roll. Recover to achieve a partial success (maybe you had to resort to some deception that can be found out). Fail both, and the target gets angry or otherwise outright rejects the attempt.

Search (CHA)

Anyone can casually explore and, 1d20, find concealed things on 15 (concealed door, most traps) and hidden things (secret doors, letter stuck to the underside of a table with wax) on a natural 20.

If you spend 10 minutes searching, you automatically find concealed things and find hidden things anywhere in the room/corridor on a 15. Name a discreet location (table, bed, 20-foot section of wall) to find anything concealed or hidden there. On a second search, you find anything hidden. Finding a secret door or trap just gives you a clue.

Stealth (DEX)

You stay quiet and unnoticed under shadowy conditions when at least 75 feet from the opponent, difficulty 8. You can hide while wearing heavy armor but not move; medium armor gets disadvantage when trying to move quietly.

This can be used to perform a sneak attack: you get advantage to your attack and, if you use a short weapon, score an automatic critical hit against a person (not any creature) when attacking from behind or otherwise undetected (invisible, etc.).

Combat

Combat rounds are 15 seconds long. You can ready an action to use before initiative is rolled.

Initiative

Resolve any readied actions first. These are simultaneous.

If no character seizes the initiative, each side rolls 1d20. Give a bonus to one side if it has significantly more characters, are of significantly higher level, or are more prepared. Deal with a character chosen by the winning side, then a character chosen by the other side, alternating until all characters have gone thru all their available actions. It may help to group some monsters together (three goblin slingmen all going at once, for example) and treat non-combatants like any other character.

Initiative is not rolled each round. However, an area-effect spell or some other disruption could cause the combatants to pause—ducking for cover or shading their eyes—and prompt a new initiative.

Actions

You typically have an attack action and a maneuver. You can take convert your attack action to a second maneuver but not vice versa.

These are common attack actions:

• Make one melee or missile attack (typical at low level)
• Make multiple melee or missile attacks (if allowed by a class feature)
• Cast a cantrip.

These are common maneuvers:

• close for melee up to 45 feet
• withdraw from melee up to 30 feet (must be able move straight back 5 feet to start)
• charge up to 90 feet in a straight line
• nock and shoot a bow
• Make a thrown weapon attack, if you have that skill
• perform a hand-to-hand maneuver, if your melee attack hit
• load a medium crossbow
• sacrifice your shield to block a hit (see Shield Sacrifice)
• something else (pull a lever, jump, drink a potion you have handy, etc.)

Each of these costs two maneuvers. You must perform both in the same round.

• rush up to 90 feet
• run up to 240 feet in a straight line, as chasing or fleeing
• cast a spell

It takes 1 round to load a medium crossbow. It takes 2 rounds to load a heavy crossbow, a weapon of war that uses a windlass and is not effective for adventuring.

Attacking

Roll 1d20 and add any relevant attack modifiers.

• Natural 1 is always a complete miss, and—for missile weapons—the arrow, bolt, dagger, etc. is lost or broken.
• An attack that can’t hit AC 10 is a complete miss—dodged or whiffed.
• An attack that can hit AC 10 but not the opponent’s AC is a glancing blow (if the damage roll is low) or block (high damage roll).
• An attack that’s 1 point shy of hitting forces the opponent to move 5 feet or take half damage.

Charging & Withdrawing

If you charge (as a maneuver), you take the initiative unless the opponent has reach (weapon with the reach trait or long limbs). You also get advantage on your first melee attack and damage, if it hits.

Any character can add +2 to their own armor class each round of combat that they move backwards 5 feet. This stacks with your tactical bonus for your own armor class only.

Shield Sacrifice

If you use a shield, you can choose to sacrifice your shield to block all damage from one attack after learning how much damage it would be. A magic shield merely breaks a strap and so can be repaired by an armorer.

Subdual

An attack to subdue is a melee attack that does half damage. If such an attack would reduce the opponent to zero hp, it instead stops the opponent from fighting and puts you in a position to kill the opponent (blade to the throat, etc.). If the opponent tries to break free, it must succeed on a contested STR check with disadvantage; you still get normal damage. Failure allows you to execute them.

Hand-to-Hand maneuvers

Sometimes, your melee attack roll allows you perform a hand-to-hand combat maneuver, if your opponent is a humanoid the same size or one size smaller. If you hit with the values below as your natural roll and your opponent does not hit in this round, you can perform that maneuver or any maneuver of a lesser roll.

For example, if you hit your opponent with a natural 15 plus your modifiers, you can perform a grapple or tackle in addition to your weapon damage. If your roll plus modifiers doesn’t hit, or if your opponent also hits you, you can’t perform a maneuver.

• A distance means a distance equal to your height. (5 feet for human, but 10 feet for ogre)
• You can’t fight most non-humanoids with these techniques.

15+: Tackle/Shieldbash: If you use a shield, you can instead do 1d3 damage with it. If you don’t use a shield, you can tackle your opponent, pushing him or her back 5 feet; you both go down; you now have the opponent in a grapple on the ground, per below.

16+: Grapple: You can take hold of your opponent in a standing grapple. The next round, the opponent must make an opposed strength check to break the hold. Otherwise, the opponent can’t take an action, and you can:

• Move the opponent a distance in any direction (if standing).
• Drop your weapon and draw a dagger for an automatic hit; if you win another opposed strength check, the opponent must (unless immune to precision damage) save vs death or be reduced to zero hp; otherwise the opponent takes normal damage.
• (Biting creatures) get an automatic hit with the bite.

17+: Shove: You can shove or kick your opponent back a distance away from you. A smaller opponent is also knocked prone.

18+: Weapon Effect: You can use an effect based on your weapon type.

• Axes: Immediate free attack at disadvantage on the same opponent or (if relevant) chop off an appendage like a tentacle or tendril (not an arm or head), depriving it of an attack.
• Swords: +2 damage or chop appendage (as ax) or opponent must make an opposed DEX check or be disarmed.
• Bludgeons: +2 damage & shove effect.
• Piercing weapons: +3 damage and opponent gets -2 to AC.

19+: Knockdown: You can knock your opponent back a distance away from you and prone. A smaller opponent also takes an additional 1d4 hp damage. In either case, you can get a free attack by advancing.

20: Critical Hit: Maximum damage plus normal damage. This is a feature is available only to creatures of 2 HD or more.

Injury & Death

Bloodied: At half hit points, you are bloodied (noticeably injured); monsters must check morale when bloodied.

Injured: When reduced to 5 hp or less, you are injured and get disadvantage on attack rolls and physical skill and ability checks. Roll 1d6 for the location on the table below.

Seriously Injured: When reduced to zero hp, you are seriously injured and could die. Roll for hit location. Save vs death.

1d6	Injury Location	Conscious?
1	Leg	Yes
2	Left arm	Yes
3	Right arm	Yes
4-5	Torso	CON check
6	Head	No

• On a success, you’re stable at zero hp and can crawl STR feet per round, if conscious.
• On a failure, you fall unconscious until allies aid you, then roll again with a penalty of -1 per round until you got aid.
  • If you succeed, you are stable at zero hp and now conscious but cannot crawl.
  • If you fail, you’ve died from your wounds.

If you survive, you’ll have a scar there. If you take more damage while at zero hp, you die immediately.

Ferocious Resistance

Monsters of 5 HD and above get one ferocious resistance; those with 10+ HD get two. Spend a ferocious resistance to:

• Succeed at a saving throw it would have failed by throwing off the effect but taking 2d6 damage.
• Avoid the damage of one attack that would reduce it to zero hit points by instead taking a major scar or suffering the loss of a limb (including a tentacle). Except for undead, such creatures will almost always try to flee.

Great Blow

If you kill a creature with an attack that does 10 or more points of damage, you chop off its head, crush its skull or spine, or pierce it thru the heart or throat, etc., as appropriate for the weapon. This could even be kicking or throwing the creature from a height or grabbing it as a shield to absorb the fatal strike from its own ally.

Falling Damage

While you can purposely jump as much as 5 feet without damage, if you fall and land on a hard surface, save vs half the height in feet (so, 10 for a 20-foot fall).

• If you succeed, take 1d4 hp damage per 5 feet.
• If you fail, you’re reduced to zero hp by a serious injury. See Injury & Death above for effects of being reduced to zero hp.

If you tumble down a staircase or a steep slope, you take 1d4 hp per 10 feet and don’t need to make a save.

Resting and Healing

If you have been seriously injured, even with full magical healing, you will retain the -2 injured penalty until you get a good night’s rest.

Otherwise, you can bind wounds and sleep at least 6 hours to regain all once-a-day powers and 2 hp per level (or, if sleeping in heavy armor or interrupted by attack, 1 hp/lvl).

Magic Items

Magic items that are rarer than uncommon require 24 hours to attune to them to use their magic. You can attune to a number of such magic items equal to 2 plus your charisma bonus.

Potions are 3 ounces of liquid and come in a glass, ceramic, or pewter container with a cork. They spoil between adventures, but you can sometimes find the key ingredient in (recent) treasure; such items can often be brewed into two different potions at a cost of half the value of the potion. (The potion could then be sold for full value.)

• Heart of a hell hound: fire resistance or fire breath
• Heart of a giant: giant control or giant strenth
• Heart of a creature with invisibility power: invisibility or true sight