Dungeonworld using 1d20

I've been using in my sessions a variant of DW using d20 instead of 2d6. Basically, the rule is as follows:

When you try to do something risky, roll 1d20 and compare the number with the appropriate stat.

If number is higher than the stat, your result is Failure
If the number is equal or less than the stat, your result is a Tie
If the number is less than the success margin of the stat (stat/2, rounded down), your result is a success.

On a Failure, the MC makes a hard move
On a Tie, the MC makes a soft move
On a success, there are no consequences.

Basically, that's the World of Dungeons hack of DW, made by John Harper, but using the d20. You just need to use the values for the stats of DW but, instead of using the modifiers, you just use the raw value. Many players digged the idea of using the ol' d20. I, personally, am very fond of it.

For the modifiers of actions, every +1 is counted as +2 when using d20. So, if you have +1 when doing an action, it's +2 if you use this hack.

What do you think about this?

Here is a link to the WD (world of dungeons)
http://mightyatom.blogspot.com.br/2012/06/world-of-dungeons.html

and a link to the WD of Warhammer
https://docs.google.com/file/d/0B5K_Bqfr0dqcVUFZeWpsa0E5T0k/edit

Why?

I mean, having it be 2d6 has a bunch of reasons. First of all, makes more result be 7-9, which allows the MC to screw with the players a bunch. You want that. And it's still success, which makes the players happy. It's win-win.

On top of that, everybody has D6s, and they end up being a lot less scary to new players then creepier, weirder dice.

My main issue with doing that is that it makes the bell curve into a straight line, and thus becomes crazy swingy. I like 7-9 to be the expected result. Because that's something I can work with, and it makes the other 2 possible result seem special. Bell curves.

I've been using in my sessions a variant of DW using d20 instead of 2d6.

Have you looked at the Talislanta RPG?

Vincent even gives some credit to Tal in the back of Apocalypse World. Heck, John Harper worked on the 4th edition of the game.

Talislanta uses a d20 and has a chart similar to AW and DW, although I'd change the values around slightly.

Why? Because it's fun using d20. It has a feel that no other dice can supply. It's something that brings us back to ADED, or at least the naive visions of ADED in ages past.

About the probability, let's talk a little about it:

These are the chances of a 2d6+0

2D6 Dice % of % Chance
Total Combos Result of this total or higher
2 1 2.8% 100.0%
3 2 5.6% 97.2%
4 3 8.3% 91.7%
5 4 11.1% 83.4%
6 5 13.9% 72.2%
7 6 16.7% 58.4%
8 5 13.9% 41.7%
9 4 11.1% 27.8%
10 3 8.3% 16.7%
11 2 5.6% 8.4%
12 1 2.8% 2.8%

As you can see, a chance of a weak hit (7 to 9) is about 40%, and the chance of a hit (7+) is 58%.

Most of the attributes in DW are above 10. If they are 10, the chance of a hit is 50%, and the chance of a weak hit is 25%, and the strong is 25%.

I use the spread of 15/13/11/10/9/8 at the starting characters. It's true that the probabilities are different, but it doesn't affect much of the game, at least in my games.

This is a cute idea, not a true mathematical transcription of the 2d6 usage to 1d20. Far from it. It's just as naive as once were players in ADED era. At least I was.

Anyway, you are free for ignoring it. You are also free to use the extra rule of the margin of success being 1/4 or 1/3 of the attribute. If you calculate the probabilities, you will see that the 1/4 is very close with the 2d6 use of the die. But I really don't mind with that.

Songs like an interesting minor hack. If I played more DW than I do, I might give it a try.

Out is certainly fun rolling d20s  :-D

I'm confused. The 7-9 result is the most common result on the 2D6 for intended reasons, and it provides the most 'grist for the mill' in terms of success with consequences.
How do you marry all those wonderful move results across to this paradigm?
Is a tie = 7-9 when you read the move results, or have you discarded them all in favour of your World of Dungeons inspired 'something risky'?

The thought sequence behind this idea is very simple: We used to roll less or equal in ADED for attributes tests. So, let's do the same with DW. But, since DW uses a 3 branched result tree, let's add the 1/2 success margin.

It's flawed, it's not balanced and it doesn't work well with DW, but it works fine with WD (world of dungeons), although flawed too. Since we play most of WD, with more improvisation than pre-set movesets, we used these rules for the fun of it. The mindset behind those rules are just 'simplicity' and 'fun'. I'm not saying that those lack in DW; on the contrary, I imagine both are inherent of it. I'm just elucidating the thought process that went into the 'making' of those rules. As you see, it was made at the heat of the moment where me and my players though: "Hey, you know what would be cool?".

And you can imagine that other ideas besides that one arose. There are other options, really, for a more 'balanced' way. If you want to emulate the 2d6 with 1d20, you can do as follows:

1-8 = Failure (40%)
9-17 = Tie (45%)
18+ = Success (15%)

In 2d6, the chances for F, T and S are, respectively, with a modifier of 0,  41,6%, 41,7% and 16,7%.

Every +1 bonus in the old 2d6, you can count as +2 in the 1d20. It's not a pixel perfect conversion, for the 1d20 is a linear progression, while 2d6 is not. But it works and it can be used as a more 'betterer' conversion of the DW rulesets.

You may even call those rules 'ADED 1d20', for the first, and 'd20 1d20', for the latter, even though they are not like those rules anyway. Maybe you can call it 1d20- de ADED and 1d20+ the d20, I don't know, lol.

Ps: I remembered other design choice behind the 'ADED 1d20'. Using the rule of rolling under the attribute requires almost none calculation, just matching the number with the attribute. I remember one of the players telling something about that and I riposting 'ok, so we can make like that'. It was cool at the moment.

Well, to be fair, if it doesn't change much, statistically, why bother?

That being said, if your reason is "Because I love my D20s!" by all means, do not let me stop you!

I've seen this done before and I always argue for the bell curve of the 2d6 because as mentioned, d20 results are all over the place and don't replicate real-world performance. But if it works for a group and they find that fun, then what the hell, why not?