5 Hours through the entire normal difficulty would have to involve getting in groups with higher level players and just running through. Which, if that's the way you want to play, that's your business. But doing that then complaining about the game being short is laughable.
There's no comparison between this and Diablo 2. Diablo 2 locations may have been larger on average, but there was no variety. They wanted every tile to be possible to connect randomly, so there was very little variety, and most locations made very little sense. You just waded through rooms and rooms of the same stuff. Even different dungeons in the same act reused a lot of the same tiles.
In this game, it feels a lot less repetitive because most indoor locations have their own art style, and the level of detail is amazing.
Act ILocation Examples: (possible minor spoilers)_
Look at Act 1 of Diablo 2, then compare it to Act 1 of Diablo 3. All the outdoor areas look pretty much teh same in Diablo 2. In Diablo 3, the Fields of Misery, the Highlands, and the early level fields around town all have completely distinct feels. Look at the dungeons in Diablo 2 Act 1. Things were all very similar. In Diablo 3, The Manor, the caves with the spiders, the caves with the khazra, and teh cathedral all have completely dinstive styles, and mostly use thier own art assets. Instead of feeling like someone made a few tyles and then recycled them to stretch the game out to the length they needed, they actually offer a solid sense of progresssion, and lots of visual diversity.
It's a hack and slash game. It can be beaten fast, or you can take your time and enjoy the acting, the art, and the story. Either way, once you are done, whether it takes 5 hours or 24, you have tons or replayability at higher difficulty levels. I am sure right now that 4 years from now, I will get in moods where I want to break out the crazy gear I've collected over the years and go blow up legions of enemies by myself or with my friends.
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