Here’s how to run Apocalypse World, Dungeon World, etc. with d20s instead of 2d6.
This is just for fun. Not claiming it’s “better” than 2d6. Just for anyone interested to try it to capture the rolling a d20 vibe.
For a straight up d20 roll with no modifiers, use this:
1-8: Failure (mark XP)
9-16: Partial success
17-20: Best outcome
Then adjust bonuses like so:
In general, you can just double a modifier, like when you move +1 forward, just move +2 forward instead.
Doubling modifiers like this makes it a bit less accurate than the 2d6 model, but much easier to use and remember. The trade off should still work fine.
This approach is remarkably similar to rolling a 2d6. Not down to the penny or anything, but totally workable if you want to try a d20 roll for fun.