Difficulty Checks

UPDATE: I no longer like Difficulty Checks at all, and I never use them.

I like the 5th edition skill check system, despite the fact that it is the most hated feature of modern D&D to OSR circles. I liked them even back in 4th Edition, when they were part of the Skill Challenge encounter system, and in my 5e games I run skill challenges all the time.

Frankly, I find the d20 + ability modifier + proficiency bonus (optional) mechanic to be simple, elegant, and nearly universal for resolving undefined actions. It's a much better system than 2e's Non-weapon proficiency and 3e's skills. The 2e and 3e systems were actually very restrictive on characters who didn't choose the skill, as it meant that the player could not even attempt an action that they didn't have the skill for. The 5e system is very different, choosing a skill only applies an optional ability bonus, and anything else can be attempted simply by rolling a d20 and applying an appropriate attribute modifier. This actually frees player characters to attempt anything, and their chance of success is modified by their personal attributes.

I like this system so much I'm back porting it into my 1e game. This solves a lot of issues I have when resolving the outcome of player actions. Otherwise, I either have to give players a 100% chance of success solely dependent on their ability to convince me that their plan would work, or invent some contrived system involving percentile dice, or a chance out of 6, or something else complicated and obtuse. That sort of refereeing led to all the exceptional cases and disassociated mechanics that plague the 1e DMG.

The 5e difficulty check is the best iteration of the mechanic. The result of the modified roll is compared against a difficulty class table that is universal for player characters of all levels, and the referee only has to choose whether the difficulty of success is easy, moderate, hard, or nearly impossible. This is quick, simple, and usually able to reach the consensus of the players without argument.

But importantly, this is invaluable in solo play when there is no mechanic for solving a problem. The OSR technique for overcoming an unknown obstacle is to convince the dungeon master of your action's attempt, but this cannot be done solo. You either give yourself a 100% chance of success, or avoid the attempt entirely. A difficulty check now allows you to play solo and attempt anything, with the vague notion that your success or failure is fairly adjudicated by the dice and the makeup of your player character. That might be too modern of an attitude for OSR D&D, but it works too well to be dismissed out of hand.

And this whole thing was inspired by me asking the question "how do you open a lock without a thief in the party?"

and here's some answers I like: https://followmeanddie.com/2015/02/21/locks/
http://initiativeone.blogspot.com/2013/07/has-osr-mostly-embraced-thieves.html
https://blog.d4caltrops.com/2008/06/rules-cyclopedia-hacks-and-house-rules.html