Thanks! Did you get to play the boss battle? It's the most fun part of the game :) you can skip straight to it with the Finale button in the main menu
Headshots don't do more damage though. It's a feature I decided to omit for gameplay reasons when I was working way back on the original concept of the game, but that concept changed and evolved over time and now looking back on it I see that it would have been better to include them with what the game ended up becoming.