Raven McCracken’s Synnibarr RPG takes a lot of criticism for – well, for a lot of valid reasons; but one of its poorer mechanics is this:
If “Fate” (the GM) doesn’t know how likely the players are to succeed at something, he should roll a d100. The result is the players’ chances of succeeding. A second roll is then made. If the second roll is LESS than the first roll, the players succeed.
It – almost – seems plausible until you think about it, right? But rolling a random difficulty threshold, and then rolling the same die against that threshold, is really always a 50% shot. You might as well play an RPG where you flip a coin every time anyone tries to do anything.
As this review of Synnibarr says:
“Fate [the GM] then makes a percentile die roll to determine whether the empty ship will be safe or not. The first roll is a 33. This indicates there is only a 33% chance of the boat remaining safe. Fate then rolls again. The resulting roll of 40 indicates that their ship won’t be there upon return. How and when the ship is lost is up to Fate.”
This is the stupidest thing that I’ve ever seen done within a role-playing game. Besides removing a potentially useful element from the adventure, it removes control from the GM and puts it into a pair of dice rolls; and they’re both entirely random. You could roll a 95% chance of being safe or a 5% chance of being safe, but it doesn’t matter, because there’s nobody at the switch; just a series of random encounters determined by blind idiot luck. It’s like Azathoth designed a role-playing game.
Agreed? Bad mechanic? Now check out these rules:
Missile Fire Procedure:
The firing player rolls two [d6] dice in sequence: The first is the number he must match or beat in order to score a hit, and it is modified by his status, weapon, the range, and so on. If the modified number is not matched or exceeded by the score of the second die the missile failed to hit its target.
This is from Warriors of Mars by Gygax and Blume, 1974. (I’ve also seen the same rule in a fairly recent edition of Pendragon.)
To be fair, one of the Warriors of Mars die rolls is modified by various factors. That doesn’t really change the issue, though. Rolling up a random target number on a d6 is no different than setting the target number to 3.5.
Warriors of Mars is from the very dawn of roleplaying, and Gygax would go on to create much better subsystems than this (and a few worse ones). Still, if you’re a rules hacker at all, it might be comforting to see that every RPG developer starts at level 1.