Think, the kind of Monkey Island. Think also, a software suitable for someone who is more a writer than a programmer (that would be me lol). Any suggestions?
Wadjet eye uses AGS. I would use renpy, but you'd have troubles coding a walking character on screen if you don't know a bit of python coding
In fact the character walking on the screen is the exact point where I would be the most undecided yet. Is AGS easy to use?
I heard about this tool last night and saw an Indie point and click adventure made in it: http://opensludge.sourceforge.net/
This is what I was going mention too as it looks pretty fully-featured, though I can't say how easy it is to use or not however.
The 2.5D part is more difficult than other 2D engines, but I think this isn't Wintermute's fault, 2.5D is intrinsically more difficult than 2D.