Player Challenge vs. Character Challenge

[Goobahfish]

"Players need to play intelligently" is different from "this particular player doesn't like or isn't good at mysteries, so I'm going to make them solve a mystery", which is what it sounded like you were describing before.

My apologies for the lack of clarity. I try not to dish out challenges the player dislike (because I'm not crazy). It is more about challenges which split the character/player incentives. Specifically they are 'not really' challenges to the character (because to them they are just doing their thing), although sometimes they are (would you kill this orphan? how about two orphans?) but rather they exist to give the player the space to roleplay in.

When I think of "player challenge", I think of something like "Dr. Samurai really doesn't handle goats very well, so I'm going to deliberately entwine his character arc with goats because tension/drama/conflict".

ROFL... there will be goats.

Testing player knowledge should be kept light and fun with puzzles and riddles, and not be a roadblock by stopping progression of the game.

A good summary I think. The point here is that testing player knowledge shouldn't be forbidden, just not all-consuming.

As an aside:
I think solving a murder mystery by rolling is pretty bad. I feel like 'something went wrong' and as a DM, if that really happened... they would fail to solve the mystery but I would direct the play some other way (i.e. that failure has consequences but isn't a road block). I can't imagine even if a player rolled high and 'solved' the mystery that anyone would feel satisfied by the outcome. Better it remains a mystery or more clues are provided.