In what critics are calling “pointless” and “why don’t you just play PBtA”, I’ve come up with a system to play OSR games with a 2d6 rather than 1d20 to-hit.
Why? Mostly because it’s fun, but also because I’m not terribly fond of the 1d20, as classic as it is. Furthermore, if you stick with 1d6 HD and 1d6 weapon damage, you’ve got a system that you can play using only d6s, which is a selling point in itself.
The bellcurve for 2d6 is fairly slight compared to the more extreme 3d6. Boxcars and snake-eyes will appear a little less often than nat 1s and nat 20s, making crits more special. Also, bonuses are worth a lot more in this system.
The basic formula is:
2d6 ≥ 7 - (your HD/2, round DOWN) + opponent AC
As bonuses are more dramatic, the same bonuses have to be nerfed a little to work with this roll. I suggest dividing them by 2, rounding up. This means bonuses are still significant, but are not entirely broken when they hit their maximum. Along the same lines, AC is folded down: light armor (leather, gambeson, etc) has AC 1, medium armor (chainmail, scale, etc) has AC 2, and heavy armor (plate etc.) has AC 3. I’ve included an AC 4 in case you want to have a place for magic plate, dragonscale, etc.
Translating that into a table, where target numbers are roll greater than or equal to, we have:
|Atkr HD ↓
||None (0)||Light (1)||Med (2)||Heavy (3)||Magic (4)|
|Up to 1||7||8||9||10||11|