Cool idea! Using your life as your only bullet is interesting for sure. Haven't done a single level on the first try, and my goodness, the last level was tricky for sure. You hammered down the Carpe Diem theme a biiiiiit to much for my liking (it was annoying to see it pop up constantly).
The ricochet wasn't glitchy and felt believable and predictable, so the core mechanic felt solid. Even if you retry each level a bunch of time, the game feels a bit short though. I love the sense of depth that the skybox and the glowing cubes give, making the levels feel a lot larger than they really are.
Not much to say about music - it worked for me, but nothing groundbreaking. The sound effect of the bullet time-out was very fitting though.
Congrats on pulling this off on your own ^^