I must create a system, or be enslaved by another man's. I will not reason and compare: my business is to create.

- William Blake

Monday, May 20, 2024

Inverted Target 20 - Trained/Untrained

If you have been reading this blog for a while, you know I'm a big fan of Target 20.

However, in the last few days, I've been thinking of an alternative that is even simpler. I'm not the first one to have this idea - I've seem something similar in at least two or three OSR games.

Mathematically, it it's very close to Target 20, but it uses a method that resembles THAC0 and saving throws. Here it goes.

You have two numbers in your sheet, in addition to ability scores* and modifiers: Trained and Untrained.

(* I've been considering 4d4+2 or a 9, 10, 11, 12, 13, 14 array).

To succeed, you need to roll 1d20+mod, equal or over this number.

Notice that the chances of succeeding when you are untrained are about half when compared to a trained PC (e.g., by level 5, the chances are 30% and 15%).

And this replaces:

- Saving throws. I'd say every adventurer is trained in saving throws. Some classes or situations deserve a bonus.
- Skills. Thieves are trained in their usual skills. But you could add "training" to rangers, for example, to forage or find tracks.
- THAC0. Works perfectly with descending AC. Only fighters are trained in combat.
- Ability checks. If you are untrained, this is how you can attempt to do thief (or ranger,etc.) stuff.
- Spellcasting, if you want roll-to-cast.

This has some advantages over Target 20:

- Level is calculated in advance, you only roll 1d20+ability mod.
- Comparing values is even easier than addition.

I'm somewhat tempted to leave this table in the hands of the DM - the PCs just roll 1d20+mod, period, telling the DM if they are trained or not.

But, overall, Target 20 feels somewhat easier to grasp for my players - they expect bonuses over a descending number.

I am a bit doubtful about what version to use in my next game.

Anyway, if you like how THAC0 and Saving throws work in old school D&D, however, this might be  a good alternative!

Notice that the two systems can be used interchangeably, as the "trained" values are mathematically identical to suing Target 20.

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