Detect launch of app instead of level start

Is there a way to know the difference of when the app is just started versus when a level is loaded?

Here is what I am trying to achieve.

When the game first runs it zeros out the score saved in PlayerPrefs, but I want the score to save between scenes. I will be going back to my main scene and want the score to not reset when I do. Right now I am using the startup to zero out the score, if there is a different method of knowing the app had just started I will put the Playerprefs score reset code there.

Here is what I am doing

    Main Scene        >    mini game scene                               > main scene    

Zero score on start > keep score for mini game scene > load back main scene but do not reset score

Thanks in advance

Load Scene > Main Menu > Mini game scene

Never go back to the load screen. Or keep the score as a static variable.