Dice other than six-sided

I think Kraven is correct here; in the same sense that you could swap out 3d6 for d20, the reverse is also true, although I would go with a 2d10 model; while this would limit the "true one," (it becomes 2) the odds of getting it are pretty low, and it removes the 100% random that is the d20 single die decision system.

Note: this is partially in response to ctaylor saying d20 is a "single die system,'" we can nitpick around damage, but he is correct: the decision maker is the d20. And that's annoying.

I have a neat 12-sider labeled with various body parts rather than numbers. Since I don't do hit locations, it's useful if you just want to randomly choose where someone gets hurt.

Well here's how it would be easy enough to do in some ways.
Change the primary rolls from 3d6 to percentile. Start with 11=55%. With main skills like Stealth, every +5% to the roll costs 1 point (instead of +1 for every 2 points) With minor skill (PS, etc), start at 55% +10% per 1 point spent.

For combat, OCV x 10 = percentage, so OCV 3=30%. You start at the flat 55% again, plus OCV, minus d%. So Bob with 5 OCV in the present system, now has 110% OCV, -d%, to resolve what DCV he managed to hit.

Damage using funny dice is a bit tougher. How many points for a d12 of blast? How much body does a d8 do?
I propose prorating the body out of a d6; it does a maximum of 2 body per d6, so that's 1 body for every 3 points on the die. A d12 then can do 4 body max, a d8 2, and so on.
To pay for powers with other dice, you base the damage on the body it can do (as if it was a normal attack). So a Blast does up to 2 points of body for each 5 points (1d6/5 pts). That means 2.5 points per body the die can do. So if you want a d20 blast, you need to pay for a maximum of 6 body, or 15 points per d20 blast.

Now, you get into some problems here. A d6 can do zero body with a minimum roll of 1. But a roll of 1 is 4% less likely to show up per d8, roughly (12.5% vs 16.666%). So while this take a bit more math, any die can roll 0 body at 10% of its roll, approximately. That way a d10 rolls 0 body with a 1, a d20 for a 1-2, and so on. Its a minor difference in most cases but its close enough for government work.

However, minmaxers will rapidly note that some dice are more efficient for the points than others. You get max 6 body out of a d20, but 20 stun. A d8 does 2 body, but has a max stun of 8 for 5 points.

So an alternate would be to pay 1 point per max the die can roll. This gives d6 a bit of a cost break (it should cost 6) but the other dice work well for this. d8 costs 8 points, d20 costs 20/die etc.

Just the novelty I love funny dice! I wouldn't ever seriously do this, but its interesting to consider how it would be done.

I keep noodling around with 2d6+d6*3, mostly because I like the shape of the curve. Hit rolls would be 18+OCV-DCV. Characteristic rolls would be 16+(STAT/5).

Thread necromancy is cool.

I think the main thing I was thinking of was in all of the d66 charts that could be d100 charts.