Neat little game, and I only killed the old man once! Oops.
The zoom level plus inverted controls plus really fast movement speed made it pretty tricky.
A little tip: you can use button.grab_focus() to move focus to the next level button so that the player doesn't need to move their hand off the keyboard to click it. I also think I inverted into two dudes at once, which is not a sentence I ever thought I would say...