I don't remember about alternatives, neither about puzzles.
My favorite phrase in describing the CSB puzzles:
"There is always another way."
Play the game yourself, with little help.
Then watch one of the record-breaking movies
in which the game is completed in 10 minutes or
so. You will see that almost every one of the
puzzles that you solved was solved in a
different way or totally avoided. And, believe
me, another person would have solved them
in yet another way.
This 'multiple-solution' avoids many of what
might seem like a dead-end situations. A player
keeps trying and suddenly discovers that a tough
problem has been surmounted as if by magic.
Or, like the Riddle Room in Dungeon Master.....
The player does not need to completely solve the
problem. Getting 75 percent of it yields most
of the reward; 100 percent adds something
special but not critical. Otherwise a player can
get totally stymied by missing one small detail.