With the latest rounds of playtesting, it's more like 30+ hours. My original 20-30 hour guess was based on my own playtesting when the game hadn't been balanced yet. And I kinda know where everything is.
I was originally worried that the original scope was going to result in a game only 15 hours long. It became very clear during development that things had grown SIGNIFICANTLY, and that my estimates were way off. And that I was never gonna get the game done if I didn't cut scope. A LOT. So I basically had to either shrink the game down by a tremendous amount (and cut out some work that's already been done… not a huge loss, but it's something), or break the game into component pieces that would be appropriate for an indie game.
Considering the first act is about double the play length of what I'd originally expected of the entire trilogy, I'm not too worried about that.
Also - I did some things that were kind of stupid if I really wanted to pad out the game length (which could have easily been double this if I'd let it…) The Drama Star thing… which basically gives you a bonus for NOT going back and re-playing content until you "get it right" probably shortens the play time a bit. I also avoided throwing in much that would be considered "filler." Most quests don't require much back-tracking between areas. And I deliberately avoided a design that would encourage players to "grind." If you run straight through the game, hitting some or most of the "optional" dungeons & so forth, you'll be in fine shape for the end-game, power-wise.
It's how I roll. I don't want to deliberately waste my players' time.
The testers could probably speak to its length a little better than me, as I have trouble seeing the forests for the trees. But my feeling was that I'd rather have a shorter game of X really entertaining hours than a longer game of 2X "meh" hours.
And while I'm still trying to cater to the hardcore crowd, I'd like to make sure the average player has a chance of seeing the end-game.
I don't think most players will be at all disappointed with its length.