At first I was confused why it looked like you could go back in the levels even though you don't need to, but after the money part it was like a revelation to me. Really great game and cool concept!

Just FYI: I uploaded the video from when I played your game on stream. You can check it out here (timestamps for each game are in the description): https://www.youtube.com/watch?v=zndBygTNM2w

I like the audio slowdown effect; that sounded really cool.

Starting the game, I died the first two times without even knowing what happened; if you don't commit running from the very first moment, you'll get killed without even knowing what happend; this is something you might want to change, especially for the first level to make sure people can get used to how the game works.

Some levels had no bullets spawn at all, but I can see where you were going with this. I loved the attempt at bullet time.