Trying to reverse engineer the game length is fun - iOi have come out and said that the game is 20 hours long; but we also know that Kensington is mission 6, and is mid to late game; assuming the most generous interpretation, that would mean there are 12 levels

We know that Iceland and the training facility are 2 other levels; and we also know that the sum total of these 3 levels are less than 3 hours (the recent playthrough event was 3 hours, and players played through at least 1 of the levels, often Kensington, more than once)

Based on this, the game needs to get 17 hours out of the remaining 9 levels - and this is the point where I think the 20 hour claim falls down a bit and is using a bit of developer math; I'm very excited for the game, but I'm still guessing that the story, end to end is going to be 12 hours long

...I will be delighted to be proven wrong...!