The Legend of Kyrandia

Real-time:

The endgame sequence has a minor time constraint. You have only half a minute
or so to figure out how to dispose of Malcolm. It is easy to accomplish
knowing the solution, and the solution is not hard to discover, but it is a
challenge to figure it out without resurrection (i.e., getting it right the
first time).

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Reasonability:

There seem to be a number of trial-and-error puzzles: the order of gems into
the altar, exploring the Shadowlands, the mixing of and effects of potions,
the gift to your parents, the musical code, and the order of placing of the
regalia. None are particularly onerous. The gift is arguable since your are
told that the roses have multiple uses, and the order of the regalia arguably
follows tradition. There doesn't seem to be a way to avoid the green potion,
requiring either resurrection or luck to advance.

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Difficulty:

Most challenges are solved by doing obvious things, although you may not know
the result of the actions aforetime. Having the rose on hand before heading
off to the island is probably the most difficult challenge, although it is
easy to work around with save/restore, or you might get lucky. The maze is
numbingly tedious, but there's little challenge except to your patience.
Finding the combination to the bells is the most tedious trial-and-error bit,
but perhaps I missed some clue.