Great sound, nice graphics, smart hints via animation, ideal level of stressfull, well polished and balanced, fitting soundtrack.
Imo with some strategy elements (hire more employees, ability to increase space, penalty on death, bonus on 95%+ close calls, managers that increase the revenue/sec but also stress/sec), this could be an actually well-selling mobile game within another weekend.
EDIT: I want a "noone died in a year archivement" :D