This is kinda more for Mike but this is the visual novel engine that I found last year. I've yet to actually have a proper poke around with it but I have played at least two visual novels that were made on the engine.
Engine link: Ren'Py engine
VNs that were made on it:
- RE:Alistair ++
Both are made by a group called SakeVisual ( dA group is http://sakevisual.deviantart.com/ ). I've actually just checked out Visual Novel Group on dA and they've updated their affiliates since last year so not sure if others would want to have a quick look of it.
It's been a while since I played through them just to get an idea but I'll write a quick pro/cons for them from what I remember
+ Story pacing was really good especially in Ripples
+ The money making system in RE:Alistair++ was quite cool although I don't think it affected the narrative that much which was a bit of a shame
+ 'Cutscenes' were quite effective for static images.
+ Multiple endings
- Got quite repetitive with the gameplay (why do they always say "you've got a month to work out who x is"?). In a why I'd really want to expand the inventory system like Phoenix Wright lol. So repetition is an issue, we'd need to do something about it lol. Maybe slowly reveal more locations or something.
Anyway, I've downloaded them again so I'll quickly play through them again to get more ideas and I'll update this post later.