For comment, amusement, and education...
* The Laws of EndGame
1) PCs should rarely fail.
1a) If they fail, they should fail big. If they win, they should win big.
1b) Know when to call it quits.
PCs should rarely fail.
This one should be fairly obvious. There are few games where "Quit while you're still behind...it just gets worse!" (as Shadowpryde just put it) is the overwhelming theme. The truth is, even in a horror or dystopian scenario, or, well, anything to do with kobolds eating babies, some success is necessary to move the plot.
I think that's one of the problems, however, of the Amber system and why it attracts More Than Its Fair Share of munchkins. (We call them different things, but um, they smell as rotten.) The idea in Amber is that you succeed unless there's someone opposing you. That idea works... ("Until someone opposes you," I hear mumbled in the background) as far as it goes. The problem is not so much in the rule, but the degrees of application. "I'm strong," is one thing. "I can pick up a bus and lift it over my head," is a magnification of the first part of a completely different nature.
When I have PCs fail, it's usually a sign of an upcoming challenge or puzzle. Sometimes it's been merely, "This is not the way to approach this particular situation."
For example, in one of my spectacular failures of a game, I had a door leading to an important NPC. The door was black, and gave off danger signals, and it was cold. This was not the way to approach the NPC. You could knock on it to the risk of your own health... but it was a (fairly obvious, at least to me) sign that the NPC didn't want to be disturbed and they would have to be Clever.
One group in this adventure simply went through the wall.
The other, however, kept trying the door. [sigh]