I think you cannot compare two playtimes because every game is different. I found a walkthrough but there isn't a lvl that looks like my lvl 21. And I can't get through it. (Been trying for about 30 mins...) The first 20 lvls were a half an hour for me.
First 3 levels are too easy. Just a simple 'find a way out of the maze'.
On the fourth you have to shoot once or twice.
A bit uninteresting, but the music is good. 2/5