You might be right about KQ3 not supporting the mouse. But there was definitely a similar scenario in one of the first Sierra games which supported the mouse where keyboard users had to walk gingerly through some kind of cliff/obstacle scenario, while mouse users could just click on where they wanted to go.

I just picked the one from KQ3 above because it's the one that really pissed me off when I played it.

And no, I don't believe your story about your friend who didn't know about saving the game... Not because I don't think it can be played all the way through in one shot, but because I don't believe anyone who's that stupid could play it all the way through in one shot.