So according to Steam I spent 7,7h Playing Arrival: Zero Earth.
I only did 2 runs. The first one was most likely the 0,7 and the second one 7 hours with only few breaks. I do not know if there was a bug or the game is too easy, or if infinite, nonstop mayhem was actually the game design decision. IF it was, it was a GOOD one!
My plan was to play the run until I collected enough XP to unlock everything, but an appointment forced me to take a break and I never got back to it. I is strange, because I really liked the game, I would like to see the other weapons – because telephone poles from orbit is defiantly not crazy enough - but cannot motivate myself to continue.
The important thing is: Whenever I think back to my run I only think fondly. 7 hours of total, nonstop action and mayhem.

Got the game for 3,47, which got me 2h13 Minutes of great entertainment per €. That is an excellent value.