Looking for information on writing a Point & Click Adventure Engine

[Nepomuk]

Hello everybody!

As the title suggests, I am looking for information on how to write a game engine for a 2D or 2.5D point & click adventure. (You know, for games like the Monkey Island or Manic Mansion series for example.) I have a basic idea of what I would have to do and am currently researching what language would be the best choice for my requirements, but so far I have found little in the way of describing what other people have done before me.
Just to clarify:

1. Yes, I do know about projects like ScummVM, Grail or ALPACA that are open source and I have downloaded their code. I probably will have a look at them, but I don't want to copy or steal their code (plus I'll probably be using a different language anyway). My engine should be entirely my own intellectual property, as I might want to sell it (or rather: games using it) at some point and I don't want any hassle with licenses. Also, at least ScummVM is a pretty big project and going through it would most lightly take ages...
2. Yes, I do know about AGS too and no, that won't stop me from writing my own engine as it doesn't do exactly what I want my engine to do.
3. Yes, I do know it's a huge project.

What I'm really looking for is a sort of rough set of instructions on what to do or tips on what I have to do in what way. Tips on how what is a good way to split the code into various bits maybe. Hints for the ingame logic. Advice on how to decide, what exactly the player clicked on. Stuff like that. The tips should ideally be language independent too, but of course there can be examples in any language that would be understandable to someone with a background in C-style and/or bash-style languages.

So, can anyone suggest any links that would help me (but please no links to any forums competing with bytes.com, that would be against the posting guidelines) or does anyone here have experience in that kind of field and would give me some tips?

Greetings,
Nepomuk