At first I was going to give the lawnmower health, but I had already put in the "gas" as a timer and figured why not combine the mechanics. Glad you liked it :)
I definitely agree with hiding the text after the first run - if I get time to update it I'll definitely remove that, I wanted to but it was way quicker to always show it.
I'm not sure what would be a good background sound when it's off - should it just be like nature/ambience, or like squeeky wheels / gears?