You have posted this twice... but under different names.
Double posts are against the rules here at Newgrounds, mate.

So after the countdown finished, the white cat just disappeared? I'm rating one star because it is a good concept, but it is incomplete and glitchy.

I'm rating this game 0 stars not because it is bad, but because it is incomplete.

What am I supposed to do here? Like I miss some tutorial or explanation or whatever - why is there the countdown? Why the cat disappears after the countdown? Why is there no restart or pause button?

Good concept, but it could use some background music. There's plenty in the Audio Portal for your perusal.