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. There are, surprisingly, some simple ways to fix it without turning it into a hybrid with modern games, like I did with 2nd Edition.

Basics: Advanced

In general, use the advanced optional rules.

Character Creation

Roll 2d6+5. This is your charisma. Roll 5 more times and assign these to the other abilities as you like. If no score is at least 15, raise your lowest score to 15. Choose one ability for an extra +1. You can swap charisma with another score to make charisma higher but not lower.

The charisma modifier is used for reaction rolls, persuasion checks, negotiations, number of permanent magic items you can attune to, saves against charm and fear, and searches (you know people well enough to know where they might hide something).

All characters start at 2nd level with maximum hit points for their class. Thereafter, they get the average for their hit die, rounded up (ex: 4 for a d6). If you choose to allow multi-classing, allow only two classes and start those characters at 1/1 with maximum hit points for the each of the two classes.

Valid hybrid classes:

• Arcane Warrior (fighter-mage)
• Swashbuckler (fighter-rogue)
• Witch (druid-mage)
• Monk (cleric-rogue)
• Charlatan (mage-thief)

Spellcasters

Import the idea of cantrips from 5e—zero-level spells that can be cast as often as once each round. In this category, give arcane spellcasters:

• prestidigitation
• feather fall
• magic dart (a single magic missile that does 1d4+1 damage; roll to hit)

Give divine spellcasters the cantrips:

• thaumaturgy
• read languages
• divine favor (the touched creature can re-roll one specific d20 roll that is about to be made, this or the next round)

The spell fire ball does 5d6 damage (not 1d6 per level). And sleep creates a normal sleep, so sleepers awaken with any normal noise or movement (meaning only those with move silently can make an execution attempt).

Martial Classes

Martial characters (barbarians, fighters, knights, paladins, and rangers) get 1d4 they can add each round of combat to one of the following: attack, damage, their own armor class, or the armor class of an ally within 5 feet.

Additional Attack: At 4th level, these classes can attack a second time per round in place of a maneuver, but at disadvantage. At 8th level, this becomes a normal attack. At 12th level, they get an additional maneuver (so two normal attacks plus a maneuver).

Combat dominance: Starting at 3rd level, once per encounter, against creatures of less than 1 HD, you can make a number of melee attacks equal to your level and treat each hit as a kill. (If you’re unarmed, these are knockouts.) This is your action for the round. At 5th, it becomes 1+1 and rises 1 HD every odd level. Fighters and barbarians can do this twice per encounter.

Level	HD of Creatures	Example Creatures
3	less than 1	kobold, goblin
5	1+1	orc, hobgoblin
7	2+1	cavemen, lizardfolk
9	3+1	deep one, bugbear
11	4+1	ogre
13	5+1	grizzly bear, lion

Monster lore: The fighter, barbarian, and ranger get this skill. Make a successful check to identify a never-before-seen creature from old warriors’ tales (per DM) and recall a special ability or vulnerability it has.

Chivalric lore: The knight and paladin get this skill. Make a successful check to identify a magical weapon, armor, shield, etc. by recalling legends of famous knights and orders of knighthood. This could also identify coats of arms and call up other aspects of knighthood.

Magic resistance: The barbarian gets +3 on saving throws vs any magic he or she shuns (doesn’t accept to his or her benefit), per fear of magic feature. He or she thereafter only gets +1 vs that type of magic from an opponent.

Rogue Class

Rather than acrobats, assassins, and thieves, there is one class called rogue. Rogues have the basic features of thieves but may choose to swap any thief skill with an acrobat skill.

• The back-stab feature includes the possibility of assassination (it’s not like thieves are just kidding when they attack from behind). When attacking an unaware opponent from behind with a one-handed weapon, a rogue receives a +4 to attack and adds his or her 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 tightrope walking skill also allows you to make a TW check to avoid falling wherever footing is in question (slime, ice, grease, gravel, etc.)—in addition to any allowed check.

The rogue starts with the two features: back-stab, evasion, jumping, tumbling attack, or disguise. At 4th level the rogue may choose the read languages feature or any one of the other features. At 10th level, the rogue may choose the scroll use feature or any two of the other features.

Similar to martial characters, rogues get a 1d3 hero die to apply as a bonus to their attack, damage, or own armor class each round. This die cannot be added to back-stab attacks.

Skills

There are certain skills that anyone in the society has: etiquette, festival dances, basic animal handling, horse-riding, general knowledge of agriculture and religion, camping, wrestling, etc. There are others that anyone can try but which you may be genuinely skilled at.

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 climb shinny up a tree or pole as well as climb fences, ropes, steep slopes, etc. Roll to climb stone walls and cliff faces. Roll recovery to fail without injury. Fail both and you fall for some injury, but probably not from the full height you tried for.

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; unreasonable arguments or requests should be rejected outright. If the GM agrees that it’s reasonable, make the roll. Roll recovery to achieve a partial or qualified success (maybe you had to resort to some deception that can be found out). Fail both and the target gets angry or otherwise outright reject the attempt.

Search (CHA)

Anyone can casually explore and 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 20. If you spend 10 minutes searching, name a discreet location (table, bed, 20-foot section of wall) to find anything concealed or hidden there and find hidden things anywhere in the area (medium-sized room or longish corridor) on a 15; you automatically find concealed things. 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, covered by illusion, etc.).

Combat

Combat rounds are 15 seconds long.

Initiative

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 better prepared. Deal with readied actions first, then 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.

You may group some monsters together (three goblin slingmen all going at once, for example), and may decide when extra characters and non-combatants act.

Initiative is not rolled each round. However, if a spellcaster casts an area-effect spell or if there is some other disruption, you may decide it causes the combatants to pause—ducking for cover or shading their eyes—and call for initiative again.

Actions

You can make a melee attack and perform a maneuver or perform two maneuvers. These are common maneuvers.

• move half your movement rate
• shoot two arrows
• throw two daggers or darts
• perform a hand-to-hand maneuver, if your melee attack hit
• load a light crossbow
• shoot a loaded crossbow
• cast a cantrip
• something else (pull a lever, drink a potion you have handy, etc.)

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

• move your full movement rate
• load a heavy crossbow
• cast a spell

Any character can add 1d4 to their own armor class each round of combat that they move backwards 5 feet. This stacks with the martial character bonus for their own armor class only.

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. (5-6 feet for human, but 10 feet for ogre)
• You can’t fight most non-humanoids with these techniques.

1: Complete Miss: This is always a complete miss, and—for ranged weapons—the arrow, bolt, dagger, etc. is lost or broken; mark it off your inventory.

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

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 cause 1d6 hp damage plus strength bonus or (if you’re standing and not on the ground as a result of a tackle) move the opponent a distance in any direction. Biting creatures get an automatic hit with the bite instead of the hold damage.

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 and flails: trip (free attack) or disarm the opponent (DEX check), if reasonable (per GM).
• axes, swords (except rapier), and warhammers: rend the opponent’s armor or hide, causing -2 AC.
• swords, clubs, maces, spears, daggers, picks: +2 damage.
• clubs, maces, flails, and warhammers: knock back an opponent a distance.
• rapier: parry an opponent’s weapon (per GM) to take no damage from one attack.
• polearm: trip/disarm, rend, or knock back.

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.

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.

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.

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

When seriously injured in combat or a fall, roll 1d6 for the location. If you survive, you’ll have a scar there. If you are conscious, you can crawl. If you take more damage while at zero hp, you die immediately.

1d6	Legs
1	Leg/hind leg (or tail, if no legs)
2	Left arm/foreleg (or torso, if no legs)
3	Right arm/foreleg (or torso, if no legs)
4-5	Torso (or head, if no legs)
6	Head

Monsters at Zero Hit Points

Monsters of 5th level and above can 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.

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 (broken bone). See Seriously Injured, above for effects of being reduced to zero hp.

If you tumble down 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

Each character can attune to a number of permanent magic items equal to three plus his or her charisma bonus.

Searches

I would use my own search rules.