Please help me understand the meaning of the phrase "boot down" in the following text from the description of the game "Bomb Chicken":
It can double as a barrier to keep enemies away, too. But these aren’t smart bombs – your payload is as deadly to you as anyone else. When the way you get around is also the biggest danger you face, exploring becomes thrillingly tense and tricky. But as long as you’re careful, you’ll never cry fowl – and there’s little more satisfying than mastering the ‘lay and punt’ technique, where you boot a freshly-fabricated bomb down a tunnel to clear it out, or at a distant switch to open a door.
I know that the lexical meaning of the word "boot" is "to kick"/ However, I am confused by the word "down"here.
Thank you for your time.