Dungeon Master Assistance

Where anyone over 18 can share thoughts and ideas on RPGs.

D&D 5E vs. Old-School Essentials

Comparing D&D 5e to Old-School Essentials.

This is one of several reviews I am doing this year of various table top roll playing games. I am specifically comparing them to D&D 5e. I am doing this with the assumption that my readers are already familiar with D&D 5e. The following review is based only upon my reading of the rulebook. I haven’t played this yet, but I will be posting my opinion after I get a chance to play test it.

I am referring here to the fifth edition of Dungeons and Dragons as 5E and Old-School Essentials as OSE. This information is for evaluation purposes, it should not be considered official rules of the game. You can assume things that I don’t list here are basically like 5E with only minor differences.

In OSE the Dungeon Master is called the Referee.


Summary of the game system

Old-School Essentials is a popular game published by Necrotic Gnome. The original D&D game was published in 1974. Advanced Dungeons & Dragons was published in 1977 and had 2 major revisions. The first was the Basic Set published in 1981 which covered character levels 1 through 3. The second was the Expert Set published in 1983, which extended it through level 14. OSE is based on the 1980s Basic and Expert sets. It is a modern presentation of, and 100% compatible with, those Basic & Expert Rules. OSE comes in 2 flavors: Classic Fantasy that contains all content from the Basic & Expert Rules and Advanced Fantasy that adds more classes, options, magic, and monsters. They do a good job of faithfully recreating those rules, while streamlining and clarifying them.


Primary differences between Old-School Essentials and D&D 5e

Character Creation

  • Basic Character Creation: The list of classes includes the list of races. Your character will be human unless you select a different race. That race is also your class. There is a separate page of information for each class (other than human) depending on whether you are using basic or advanced character creation.
  • Advanced Character Creation: You select your race and then you select your class.
    • Other than human, each race is restricted as to which class it can be, and the maximum level you can attain in that class.
    • As an example; if you are a Dwarf you can only be an Assassin (max 9th level), Cleric* (max 8th level), Fighter (max 10th level), or Thief (max 9th level). *At the referee’s option, dwarven clerics may only exist as NPCs.
  • Roll Abilities: Roll 3d6 for each in order. [same 6 abilities as in 5E]
  • Adjust Ability Scores: Each class has a Prime Requisite ability (see below). With certain restrictions, you can raise your prime requisite by lowering other ability scores, spending 2 points for every point you raise your prime requisite ability.
  • Ability Score Modifiers: Each ability has its own set of ability modifiers. For example, here are the ability modifiers for Strength:

           STR          Melee                 Open Doors

           3                 –3                           1-in-6

           4–5             –2                           1-in-6

           6–8             –1                           1-in-6

           9–12            None                     2-in-6

           13–15         +1                           3-in-6

           16–17         +2                           4-in-6

           18                +3                           5-in-6

    • Your INT determines how many languages you know. Your WIS determines Magic save bonus. Your DEX modifies your armor class, your missile attack rolls, and intuitive rolls. Your CON modifies your hit points.  Your CHA modifies NPC reactions and determines your Max # of retainers and their loyalty.
    • Your Prime Requisite ability (determined by your class) determines your XP modifier that is applied whenever you receive experience points.
  • Attack Values: Refer to THAC0 below.
  • Saving Throws and Class Abilities: Record your class abilities and your saving throws. If using the optional rule for weapon proficiency, record which weapons you are proficient with.
  • Hit Points: You have to roll your hit points at first level. No exceptions.
    • Modify by your CON modifier.
    • Optional Rule: You can re-roll a 1 or 2 (before applying any CON modifier).
  • Alignment: Lawful, Neutral, or Chaotic
  • Known Languages: This always includes the common tongue and your character’s alignment language.
  • Background: Roll on a table to see what your character did before becoming an adventurer. 
  • Determine Secondary Skills (Optional Rule): Roll on the table, or select a secondary skill.
  • Starting Gold: Everyone starts with 3d6 × 10 gold pieces.
  • Purchase Gear: Purchase your equipment from the equipment lists.
  • Armour [Armor] Class: Determined by your armor and DEX.
  • Level and XP: Start at 1st level with 0 XP.
  • Name Your Character: Give him or her a name and you are ready to play.

THAC0 “to hit armor class zero”

  • When Third Edition Dungeons and Dragons came out they dropped THAC0. They were able to do this by completely changing armor class. Back when they were using THAC0, lower Armor Class scores were better, so bonuses decreased your AC and penalties increased it. To maximize compatibility with the earlier versions of D&D, OSE uses these earlier rules. When you attack, if the attack roll is equal to or lower than the opponent’s AC, the attack hits. When you attack a monster, you find your character’s THAC0 on the Attack Matrix and look across it to find the number listed under the AC for the monster to find the number you need (or lower) to hit it. You will want to copy this row from the table onto your character sheet for easy reference.
  • Ascending AC (Optional Rule): OSE has this optional rule so you can roll the monster’s AC or higher to hit [like in 5E]. So everywhere it lists an AC or THAC0 it shows the corresponding AC or bonus to hit in square brackets for you to use. It does note that “Using Ascending Armour Class results in very slightly different attack probabilities than when using the traditional approach of descending AC with an attack matrix”.


  • OSE Classic Fantasy: Your character can be a Cleric, Fighter, Thief, Elf, Magic-User, Halfling, or Dwarf.
  • OSE Advanced Fantasy: Adds Acrobat, Assassin, Barbarian, Bard, Druid, Illusionist, Knight, Paladin, and Ranger.
  • Some classes have a minimum requirement. For instance, to be a Paladin you must have a minimum CHA of 9.
  • Each class has a hit dice, a maximum level, a list of the armor you can wear, and weapons you can use. And the languages you get for being this class.
  • A class may have other requirements. For example, a Paladin must be lawful. If a Paladin ever changes alignment, he loses all class abilities and becomes a fighter of the same level.
  • Each class has its own level progression table that shows: XP required, Hit Die, THAC0 and saving throws for D: Death/poison; W: Wands; P: Paralysis/petrify; B: Breath attacks; S: Spells/rods/staves. If the class casts spells, it also shows the number and level of spells you can cast at each level.
  • Each class also has additional features.

Multiple Classes (Optional Rule)

  • A character may be of up to three classes, which are selected at character creation.
  • When earning XP, the total earned is split evenly between the per-class XP counts.
  • When the character has gained enough XP in one of their classes, that class increases in level.


  • OSE Classic Fantasy: You can choose to play a Dwarf, Elf, Halfling, or Human.
  • OSE Advanced Fantasy: Adds  Drow, Duergar, Gnome, Half-Elf, Half-Orc, and
  • Infravision: All races except Halfling and Human have infavision [Similar to darkvision]. It allows you to see heat energy. Visible light and large heat sources disrupt it.

XP and character level advancement

  • Experience Points
    • XP is gained from treasure recovered and monsters defeated.
    • Your ability score in your Prime Requisite gives you a modifier that you add to your experience points as you get them.
  • Leveling Up
    • The class levels range from 1 to 14.
    • All non-human races, when chosen as a class, have a maximum level lower than 14, depending on the race.
    • Each class requires a different number of XP to advance to higher levels.


Each round of combat (10 seconds of game time.):

  1. Declare spells and melee movement: Players must inform the referee if they intend to cast a spell or move.
  2. Initiative: Each side rolls 1d6 at the start of each round. (Referee rolls for monsters and one of the players rolls for their side.) The side with the highest roll acts first.
    1. Ties: Either both sides may roll again or actions on both sides may be resolved simultaneously. (This means that both your character and the monster he is fighting might die!)
    2. Slow Weapons: Combatants attacking with two-handed melee weapons always act last in the round.
  3. Winning side acts:
    1. Monster morale (Optional Rule): Monsters have a listing for morale, rated from 2 to 12, which represents how likely they are to fight or flee.
    2. Movement:
      1. If not in melee combat: you can move up to your combat move rate.
      2. When in melee:
        1. Fighting withdrawal: You can move backwards at up to half your combat move rate.
        2. Retreat: You turn and flee, moving up to your combat movement rate. This round you may not attack; your opponent gains a +2 bonus to all attacks against you and you get no shield AC bonus.
      3. Missile attacks: Opponents must be more than 5’ from one another.
        1. Short range: +1 bonus to attack rolls.
        2. Medium range: No bonuses or penalties.
        3. Long range: –1 penalty to attack rolls.
  1. Spell casting: You can’t take any other actions or move this round.
    1. Line of sight: The target must be visible to the caster.
    2. Disrupting Spells: If you lose initiative and are successfully attacked or fail a saving throw before your turn, the spell fails and is removed from your memory.
  2. Melee attacks: Opponents must be 5’ or less from each other. You can move and attack on the same round. You normally get one attack per round. PC attacks inflict 1d6 damage. Melee attack damage is modified by your STR.
  1. Other side acts: In initiative order.

Healing and Death

  • Healing
    • Natural Healing: For each full day of complete rest, a character recovers 1d3 hit points.
    • Magical Healing: Magical healing and natural healing can be combined.
  • Death: A character or monster reduced to 0 hit points or less is killed.
    • Limits on Returning from Death (Optional Rule)
      • Number of Times: A character’s initial CON score defines the number of times that they can be returned from the dead by magic.
      • Chance of Success: The chance of resurrection magic succeeding depends on a character’s CON score.
      • CON Loss: Each time a character is brought back from the dead, their CON score is reduced by one point.

Magic and spell casting

  • A 1st level magic-user has one spell in their spell book, selected by the referee (who may allow the player to choose).
  • Spells in memory: The character’s level determines how many spells they can memorize at one time.
  • Reversible spells: Some spells are reversible; this is indicated in each spell’s description.
  • Memorizing Spells
    • Rest and time requirements: You can memorize new spells after an uninterrupted night’s sleep. One hour to memorize all spells you are capable of memorizing.
    • Duplicate spells: You may memorize the same spell more than once.
  • Casting Spells
    • Once only: When you cast a spell, knowledge of the spell is erased from your mind.
    • Freedom: You cannot cast spells if gagged, bound, or in an area of magical silence.
    • Line of sight: The target of the spell must be visible to the caster.
  • Spell Effects
    • Concentration: A spell might require concentration to maintain its effect. Performing any other action or being distracted causes concentration to end.
  • Arcane Magic
    • Memorizing Spells: Arcane spell casters memorize spells from their spell books.
    • Reversing Spells: The normal or reversed form of a spell must be selected when the spell is memorized.
  • Divine Magic
    • Memorizing Spells: When praying for spells, divine spell casters may choose any spells in their class’ spell list that they are of high enough level to cast.
    • Reversing Spells: Divine spell casters can cast the reversed version of a spell by speaking the words and performing the gestures backwards when it is cast.
    • Deity Disfavor: If the character ever falls from favor with their deity, penalties may be imposed.

 What you need to get started

Everything you need is available on Necrotic Gnome’s web site.

This site has a free copy of Old-School Essentials Basic Rules which has enough information to roll up some characters and play a low-level game.

Their site also contains character sheets, spell trackers, and other free downloads. It also has a complete online rules reference and more. Of course, you can also purchase their rule books, accessories, supplements, and adventures.

To play Classic Fantasy, you only need the single Classic Fantasy Rules Tome.

To play Advanced Fantasy, you need the Advanced Fantasy Players Tome and the Referees Tome. These two books also include everything from the Classic Fantasy Rules Tome, so there is no need to purchase that one if you choose to go with Advanced Fantasy.

Final Thoughts

  • No Advantage/Disadvantage.
  • No proficiency bonus.
  • No feats.
  • No cantrips.
  • No spell slots.
  • No spell components.
  • No sub-classes.
  • No skill system – no ranks or skill points.
  • No opportunity attacks.
  • No inspiration.
  • No death saves.
  • Old-School Essentials is largely compatible with material published for any version of D&D earlier than 3rd edition and should be 100% compatible with the 1981 Basic/Expert edition.
  • I was playing Advanced Dungeons & Dragons until Dungeons & Dragons Second Edition came out and I liked it better. I was very excited by Dungeons & Dragons 3rd Edition when it came out. I liked it better still. I didn’t care for4th Edition, so I never played that. When Dungeons & Dragons 5th Edition came out, it was everything I had hoped 4th Edition would be. I have been happy playing 5E sense it came out in 2014. However, should I want to go back to playing Advanced Dungeons & Dragons I would seriously consider playing Old-School Essentials. Those old rule books were a little confusing and OSE has done a good job of clarifying, updating and expanding on them.

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