How to port skill checks from one d20 system to another [closed]

Question

Is there a consistent way to transfer skill checks between various d20 type systems?

In D&D 5e, for example, a precedent is set for difficulty of skill checks, where 10 is easy, 15 medium and so on (or something like that, I don't have the books in front of me)

Surely it's possible to take scenarios that are inspiring from one game and place them in another, but this has the potential for the GM to make a lot of human error. I'm okay with taking a lot of time to transfer rules and playtest, but I'm wondering if there is an empirical way, a measurable and verifiable way, to transfer skill checks from any d20 system to another d20 based system. The verifyibility would be that players of an approximate power level have the same statistical capacity for success when moving from one system to another.

Is there a format or formula to follow? Have any materials been written on "porting" these skill checks and scenes?

The answer does not have to cover everything, but I am looking for something I can read that gives guidelines.

As an example, say that I made a scene I liked a lot for D&D, and wanted to port it to a new group playing in a different system more or less verbatim.

Players scale a tall seaside spire to a Roc's nest. Every 2 in-world minutes, a massive wave sends the imbalanced structure shuddering, and the players have to make a DC16 save to hold on for dear life. 150 feet up, the players are confronted with a harpy and must succeed a DC14 wisdom save (or something, I don't have the book) in order to not throw themselves off the cliff.

What are some materials or resources that I can call upon to "port" said encounter to another system? Are there any workable rules or formulas, or is it simply too broad of a question? I feel like there should be some relation to the possible success rate in games that share the same dice. I would think (perhaps incorrectly) that there is a correlation between the statistical probability of success and the number of sides on the die.

Answer 1

No In general

The problem is that skill checks didn't work exactly the same way writ large in any of the systems. A very small example is in 4e Skill Checks could also be handled by Complex checks. Those simply do not exist in 5e so there's no way to replicate them. If you go back far enough (for example 2e) the skill system didn't even work as you suggest with difficulty "classes" and 1e and Basic D&D didn't even have a skill system (but looking at the modules you will see these kinds of 'checks' typically using straight rolls or some other mechanism).

But.

Ignoring those cases, it's in most cases reasonable to do the conversion about how you suggest: Convert the numeric to the class of the skill in the system (e.g. Easy is between 10 and 15 or whatever) then convert it back to it's equivalent in 5e. That should, approximately, give you the right feel... with another caveat:

Some of the system would presume more available magical aid than 5e. So, if the effect was "or die" and the system was 3e, then that wouldn't translate as well to 5e because 5e doesn't really expect players to die often, but 3e you could buy a scroll of Raise Dead at the corner store (okay, that's an exaggeration, but, the ultimate point stands).

TLDR: You will unfortunately have to translate all of the checks on a case-by-case basis looking at both the difficulty AND the consequences of a failure and adjust accordingly.