Dungeon Blueprint: 2D20

Starting off this week with a new weekly feature in testing -- Dungeon Blueprint should focus on my own tinkering with pen and paper RPGs. In this first installment I take a brief look at a mechanic I'm thinking about using: 2D20.

The mechanic works like this: roll 2D20 and add them together along with any modifiers. If the result is 18-24 it's a success. If the result is 21 (without modifiers) it's a critical success. If the result is 2-5 or 37-40 (without modifiers) it's a critical failure. And whenever a pair is rolled up a complication occurs which may be good or bad.


The numbers behind the choices are pretty simple:

Unmodified, there is a 32% chance of success (or 68% chance of failure). I want unmodified rolls to be a bit risky but still do-able. 'Unmodified' would be skills that have been taken but not improved.

Critical success and critical failure both have a 5% chance of occurring -- similar to rolling 1D20.

Complications occur 9.52% of the time and should provide a bit of randomness to play.

How skills come into play:

Skills provide modifiers that may be used to add to or subtract from the result, essentially widening the success range. This means that early points will provide large increases (8% for the first +/- 1) while further investment will result in smaller and smaller increases -- meaning that diversity in skill choice should be encouraged but perfecting skills is possible, at a cost.

And that's the barebones of it for now. Next week I'll see about delving into the setting a bit. Spoiler: massive towers and post-apocalypse goodness.