One of the big advantages of the D20 system is that it uses the same resolution mechanic for just about everything. That is, you just roll a D20 and try to match a target number. If you beat the target number, you succeed. Sometimes there are different effects according to how much you beat the target number by.
It works well, but I've recently realized that this system confuses luck with skill. Skill is one thing. Skills is what a character does in the game. In that case, rolling the dice corresponds to some sort of action in the game world. But there are other reasons to roll dice.
The original Dungeons and Dragons (there were several "originals" so take your pick) had a rule that went, when in doubt, roll a die. You're not rolling for an action by any particular character. I liked that. There are all sorts of uses for this, from deciding what random monsters attack to procedurally generating a dungeon, to developing a character's background through lifepaths, to deciding whether a flock of flying bats knocks torches off the wall.
So what I'm proposing using a different die, and only one die, for random world events like this. Naturally, if you need an extra die, then it stands to reason it would be the standard six-sided die. Besides a D20, what other die are you more likely to have?
Let's call this the D20&D6 system. D20 for skills, D6 for random events and decisions. That ought to be all you need.
