I love scary & I love humour! But if I were to make an adventure game I would have to base it on something I know to start with.
I think it would be on my job - I do such a variety of things, often have to think very quickly about what I am going to do from week to week & also organise a lot of activities & with no walkthrough to help me!
This gives a lot of scope to integrate inventory type puzzles & many others in a logical way.
I would try to incorporate a mystery to be unravelled, at the same time it would be humourous (there is at least one thing that makes me laugh every day!!) & I would plagiarise style & ideas from the Carol Reed Mysteries, the Nancy Drew games & Sims type games (in a small way).
Ultimately it would be a game that I hoped people would find fun to play but would probably not be my first choice of game!