D:OS offers at least 60 hours of gameplay if you don't rush.
60h / 2h/day = 30 days
No game will ever again be as big as BG2. These times are definitely over. But compared to other modern games D:OS offers a lot of content and I mean hand-crafted content made with passeion and heart and not genereic content like in Skyrim...
Why is it that no game will ever be as big as BG2? Was it so big that it did something horrible that shouldn't be repeated?
No, quite the opposite. But BG2 was a pure work of passion from Bioware more or less out of their garage. The realities of the business have changed though. It's just no reasonable investment anymore to make a game that big. Even the old guys from Bioware and Black Isle admit that they were completely insane at that time with all the content for BG2.
You just can't finance a project of the size of BG2 anymore. Big publishers would never make such a big game (why should they if they can sell a much smaller game for the same price?) and even independent developers like Larian have to pay their own developers and artists and so on. If someone give them 10 million without wishing to have it back they would probably do so. But nobody is as crazy today to invest 10 million or more (which is my personal estimate to make an RPG as big as BG2 today) in such a game which only caters to a niche audience. That would be an incredibly high risk. Maybe someone will take it in the future, but I doubt it. Not even speaking about the risk that if the whole project financially failed the company would go out of market and every employee would lose their job...
