My Old School Essentials

The more games I play the more I appreciate the simplicity and brilliance of OSE and B/X. For me it’s a game that just works every time and does the job it’s supposed to do. When I play modern games or more complex older games I find myself thinking about what OSE lacks and questioning whether it is too simple. Does it need more stuff to give players variety (are all plate mail wearing fighters the same)?

There are tons of people who have asked the same questions and have presented their own take, usually in the form of options and house rules. Yet each house rule adds to the complexity of the game and takes players away from the core experience. Still, I do like to stray into this territory from time to time and see what I can pull in to enhance my game. So here are the house rules I’ll be using in new OSE games in 2021, all pulled from a variety of sources and tweaked to my own taste.

Essential House Rules

Character Creation

Attributes: Roll 3d6 for each (reroll any 3-5 result), then you can swap any two attributes.

Hit Points: Taken from LotFP, at level 1 a character will have as a minimum the average (rounded up) of their class hit points plus or minus their CON modifier. The player should roll for their level one hit points and it if it is less than this average, they will take the that instead.

Hit DiceMinimum hit point
Minimum level 1 hit points by hit dice

For every subsequent level reroll all hit dice for their class +/- CON modifier per level. If the new total exceeds the current total, that is the character’s new amount of hit points – if it is less than the current value, add 1 to the current hit points total.

Shields Shall Be Splintered!

Taken from this article by Trollsmyth, when a character with a shield takes damage they can opt to have the shield absorb all of the damage from the attack and splinter, becoming useless. It means the character no longer has a shield (unless they carry a spare), but takes no damage from that attack

This only applies to damage from regular weapons and potentially magic (at the GM’s discretion – for example, it makes sense that it could block a Magic Missile).


I generally find the Basic Encumbrance system (RT p103) more forgiving for the players, so I will do it like this:

  • Basic encumbrance is based on armour worn
  • The Carrying Treasure movement rate is triggered if the character is carrying an additional 200 coins weight in treasure
  • To avoid PCs going silly with Shields Shall be Splintered they can carry one shield on their back and have one prepared on their arm. They cannot carry any more than those two.
  • PCs can carry a number of weapons based on whether they are non-martial (2), semi-martial (3) or martial (4). A PC with a Strength of 13 or greater can carry one extra item. Two handed melee weapons take up two slots.

Alternatively I might just use Detailed Encumbrance as FoundryVTT handles that really well.

Alternative THAC0 progression

I’ve been using this for a while, for most classes it increases to hit chances in smaller increments rather than every 3/4/5 levels.

Advanced Fantasy Genre Optional Rules

In addition to the advanced fantasy classes there are a few optional rules in this book, these are the ones I will be using:

Class Abilities

  • Limits on Turning Undead
  • Magic-Users and Staves


  • Attacking with Two Weapons
  • Charging into Melee
  • Parrying
  • Splash Weapons


  • Raising the Dead
  • Spell Books and Learning Spells (also get Read Magic for free)

Under consideration

These rules all add a bit more flavour to the game at the cost of complexity. I plan on giving all of these a try with the proviso that if they don’t enhance the game I’ll drop them.

D6 Skills

Based on this fantastic article by Lucian Blumire we can see that OSE has the following skills which are resolved with a D6:

SkillOSE mechanic
ForceOpen doors (RT p108) [based on Strength]
ListenThief Hear Noise (RT p34) [based on level]
Listening at doors (RT p108) [1:6]
Dwarf, Elf, Halfing, Drow, Duergar and Gnome Listening at doors (RT p24, p26, p30, AFGR p15, p18, p21) [2:6]
LuckTriggering traps (RT p109) [2:6] invert to Avoid traps [4:6]
NavigateLosing Direction (RT p111, p112) invert to Path-Finding [based on terrain]
Druid Path-Finding (AFGR p16) [1:6 getting lost in woodlands, invert to 5:6]
Light fireTinder box (RT p43) [2:6]
SearchSearching (RT p109) [1:6]
Dwarf, Duergar, Gnome and Svirfneblin Detect Construction Tricks (RT p24, AFGR p18, p21, p34) [2:6]
Dwarf and Duergar Detect Room Traps (RT p24, AFGR p18) [2:6]
Elf, Drow and Half-Elf Detect Secret Doors (RT p26, AFGR p14, p22) [2:6]
Svirfneblin Stone Murmurs (AFGR p35) [2:6]
LoreBard Lore (AFGR p13) [2:6 chance from level 2[
Lore optionally for others [1:6]
StealthHalfling and Gnome Hiding (RT p30, AFGR p21) [2:6 in dungeon, 90% in woodlands]
Duergar Stealth (AFGR p19) [3:6 underground]
Svirfneblin Blend into Stone (AFGR p34) [4:6 gloomy, 2:6 well lit]
Forage (Group)Foraging (RT p110) [1:6]
Barbarian Foraging (AFGR p10) [2:6]
Ranger Foraging (AFGR p32) [2:6]
Hunt (Group)Hunting (RT p110) [1:6]
Barbarian Hunting (AFGR p10) [5:6]
Ranger Hunting (AFGR p32) [5:6]
Stealth (Group)Surprise Checks (RT p114) [2:6] becomes Stealth [2:6]
Ranger Surprise Attack (AFGR p32) becomes Stealth [3:6]

To complement this Thief skills can be converted to D6 skills using this table by Dyson Logos. Not sure I’d use this or just stick with the percentage skills.

How then does a thief’s Move Silently skill interact with the group Stealth skill. The way I see it, the party can be moving stealthily to perhaps gain surprise or evade an opponent, whereas the thief can use their ability to close in on opponents and move right past them almost in plain sight. Lucian Blumire expands on this in the article How I run the thief. Old-school musings on the thief class.

Boons and Knacks

Kris H published an article on Boons for OSE to help differentiate characters – so not all fighters are the same for example. In essence at level 1 and every 3rd level a character gets a boon in one of the categories:

  • Adventurer Boons (available to any class)
  • Arcane Boons (Magic Users & Elves)
  • Divine Boons (Clerics)
  • Fighting Boons (Fighters, Dwarves, Elves & Halflings)
  • Roguish Boons (Thief)

I’d expand it to include classes from the Advanced Fantasy Genre Rules, it would be quite easy to match them up. These will certainly make all characters a bit more powerful so I’d need to consider each as the players select them.

Additionally, or if I find boons are a bit too much for my OSE game I’d go with Kris H’s 100 Knacks for B/X D&D which are a little lighter and a more focussed. A character starts with one knack at level 1 and gains a further knack (or masters an existing one) every two levels. The chance of using each knack would be a base of 2:6 with these modifiers:

  • +1 for 13 or greater in a relevant attribute
  • -1 for 8 or less in a relevant attribute
  • +1 if the knack is selected a second time for mastery

This is similar to Secondary Skills in the Advanced Fantasy Genre Rules (p52) so I may just use that instead.

That’s about it; I expect this to evolve as time goes on and play experiences change my perspective – I may end up scrapping the whole thing and going back to rules as written! Are there any amazing house rules I’ve missed or bits and pieces that will enhance the game without adding too much complexity? I’d be interested to know your thoughts.

6 thoughts on “My Old School Essentials

  1. Fantastic article! Thanks for compiling your thoughts on various house rules and pulling together different options from other sources into one easy to read article.


      1. That could be useful. I have just started delving into OSE and have been running “The Keep on the Borderlands.” I have only implemented one house rule thus far. I took the resource dice concept from Forbidden Lands and am using that for things like arrows and sling bullets. It makes life so much easier than dealing with the minutiae of “how many arrows can I collect after combat?”

        Liked by 1 person

    1. I do like the Lamentations system, it works better for thieves at lower levels. I’ve also found the Whitebox Fantasy Medieval RPG version works well, basically a thief has an x-in-6 chance of doing every thief-like activity based on their level.


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