First attempt at this, went pretty good but 3 mistakes near the end that cost me around 3 minutes, so sub 14 is possible.

I didnt know when to start and finish my timer so I started from the point where the first missions menu appeared and ended when i crossed the finish line of the final mission.

Also, not really sure about the in-game time as there isnt a place where it gets calculated together nor some overall day/night cycle clock, but I can add my total times if its neccessary.