Thank you for playing!
I didn't really get enough time to add a tutorial, but there is a slow motion toggle by pressing space bar. The cat's eye at the bottom of the screen is a meter of how much "reflex time" you have left. It refills with time.
The symbols are the lives you have for the missions. If you aren't able to clear a mission in time (time left seen on the top right corner), you lose one. If you lose all three, you lose the game.