So here's an idea. I've mumbled somewhere about cutscenes and how problematic they are - the player hates standing still listening to idiots ramble especially when it's obvious they should be shooting in the speaker's face, and the designer has to nail the player's feet down to STOP them from shooting in the speaker's face especially when the speaker is supposed to be on the player's side...
What about a game where interrupting cutscenes is actually a major gameplay element?
Say you're some sort of thief or assassin character. You trail your target off to his secret lair and he, not aware of your presence, starts opening a safe that only he knows the combination to.
1. Kill him immediately, thus forfeiting the big pile of jewels inside the safe that you can't open once he's dead?
2. Let him open the safe before attacking, risking him having hidden a nice big gun in there which will make it easier for him to fight you?
Of course, if you've been doing your stalking properly ahead of time you should KNOW what he's got in that safe so that you know which option to pick.
But just - LOTS of stuff like that. Eavesdropping on conversations to get information. Pretending to be helpless to let the villain drone on about his Evil Plan before you attack him. Or being in a boss fight and stabbing the guy and have him actually start talking to try and stop you from finishing him.... he can start to tell you secrets and draw out the fight (but maybe he's stalling for time so his minions can arrive!)
This gives up two problems - what do you do if the player just slaughters everything and therefore doesn't get any of the information vital to the plot? and also, what do you do if the player just slaughters everything but reads a walkthrough and tries to continue with the plot anyway?
You'd need to design the game so that a player who missed all the clues was still channeled towards some kind of (bad) ending... For the second problem, to some extent you'd probably have to allow it, in order to let the world be somewhat open and not forced from quest-point to quest-point, but you might have some randomly generated things where if you didn't listen and get the clue (which would be recorded for you in some kind of quest journal) you can't get the reward?