if you want to do something real specific--like hit the orc's torch and knock it on the floor, you can if you roll a crit. You can also extend your crit range as much as your heart desires: natural 19-20, 18-20, 16-20, all the way up to 11-20. Your choice.
The only catch is you then have to extend your fumble range from one by the same amount.
So you really want to knock the Necronomicon out of the cultist's hand? No problem, you want it on a 15-20? Ok. But on a 1-6 you trip and accidentally stab the baby he was about to sacrifice. Or yourself. Or your dad. Or whatever your DM's cruel little heart devises.I liken this to Goodman Games Dungeon Crawl Classics RPG Mighty Deed of Arms, a rule I like a great deal (at least when I first read about it last year, I'm not sure if the rule has changed much because I have not kept up with DCC RPG's development). However, I am not a big fan of DCC RPG's action die - a separate die (d3 at first level) that is rolled along with the d20 attack roll.
Zak S's mechanic is simple, elegant, and fun. I especially like that choice involved in making the called shot more likely to hit but at the cost of increasing the chance at a fumble.
A comment by Mike Monaco brings up an interesting point:
The problem from a player's perspective will be: a really skilled swordsman or whatever (a higher level fighter) is no better at called shots than a clumsy newb -- it's all in the die roll.My answer to that comment would be the following house rule:
Fighter Critical Hits: Hero's and Superhero's are world reknown for their fighting prowess and ability to strike the critical blow to defeat their enemy. A Hero's (level 4 fighter) critical hit range is 19-20 and a Superhero's (level 8 fighter) critical hit range is 18-20.
For example, a Hero calls a shot to stab the eye of a cyclops. A roll of 19 or 20 will succeed and a roll of 1 would fumble. The Hero could increase his chances to stab the eye to a roll of 16-20, but a fumble would occur on a roll of 1-4. A level 3 Swordsmaster performing the same called shot would only stab the eye on a roll of 20 and fumble on a roll of 1. The Swordsmaster could increase his chances to stab the eye to a roll of 16-20, but a fumble would occur on a roll of 1-5.
This ability demonstrates that Fighters are the kings of battle (other classes do not increase their critical hit range) and higher level fighters are more apt to perform "mighty deeds of arms".