Very simple, but lots of fun. I love how you get sucked in and just have to focus and respond without thinking too much. Nice job!
From a game play perspective, it did take me several plays to understand that I was losing “life” because I wasn’t pressing the space bar at the right time. What threw me off was that the game started off with with having me match squares and your “life” is represented with the same shape, so when they fell off I thought that I was trying to just match 3 squares to complete the level. But once I got it, it worked well from there.
If you are going to work on it more, I think sound would add a lot. And making some crazy moving backgrounds that force you to focus more and get into the “zone” might be fun.