Related to yesterday, in my desire for systems that "get out of the way" I often substitute a rule from one game for another.
Day 22 Substitute
When I write a supplement or a core rule book I assume that people are going to play it more or less as written. At least that is, one time. After that I make no assumptions of how someone is going to play something. Generally speaking, I also don't play things rules as written. I am always substituting one set of rules for another.
In Post-2000 D&D skills are much better defined than they are in previous versions. So I find when running an older version of D&D (say AD&D or Basic-era D&D) then I find myself often asking my players for a skill check. To make life easier for all of us I will typically use 5e style names and tell them what they need to roll. It moves the game along faster in most respects.
I am not limited to substituting one form of D&D for another. I will also grab ideas from other games. I will for example allow a character to use a skill that is not tied to a particular ability. For example, in Unisystem the skills are independent of Abilities. So the Art skill can be tied to Intelligence for knowledge of a particular bit of art. Or use it with Perception to determine if a piece of art is a fake. Or with Dexterity to create a piece of art. In D&D 3, Knowledge is always tied to Intelligence. But sometimes I let characters tie it to Wisdom if they came upon their knowledge via practical experience instead.
And these are just for skills. I use the Bloodied condition from 4e for some monsters in combat. I use the conditions from 5e in old school games, and more publically I use the 5e size modifiers in almost all my D&D games now.
In some ways, though I still prefer AD&D 2nd ed, d10 initiative roll, but 3e-5e's d20 works roughly the same way.
What rules do you like to substitute?
