Very nice idea !
It was fun playing through it , my eyes were constantly on the mission board, i also realized i can kill faster while pressing spacebar while i was clicking on the red skull, which made the process go faster. i believe i took less than 15 mins to finish it
Also this is just a personal correlation of mine , but i was recently watching "Jupiter Ascending" movie, and there the "owners of earth" say how they were preparing earth for its "Harvesting" which was basically the same as this game, kill everything and harvest the souls, so when i played this game, it made me connect to that .