Using two UI bug exploits, I estimate you could unlock 100% in about 35 minutes. works on browser and also android.
First, the HP you lose after an activity does not trigger until after the main screen has faded in. You can avoid the damage and gameover screen by clicking the heart when the main screen is fading in after finishing an activity, taking you to the status screen.
Second, when you are in the status screen, you can use the arrow buttons to select which screen you want to go to next, you just have to count it , eg; click right 6 times to select the first activity, then press the heart to get back to the main screen but press it again before it fades in and you will go to the activity.