Really good game with distinct and well thought out boss fights.
There are nice little intricacies in character movement and shooting, but I think an in-game tutorial wouldn't hurt. I got stuck on Rust until I checked the controls and found the slow walk.
Finding optional bosses was fun, but aside from that and one upgrade, there are not a lot of Metroidvania elements.
I died a couple of times right after defeating a boss, specifically on Python and Rust.
The respawn fade-in could've been a little bit faster. It was quicker to just go into the menu and load the game.
The platforming on the way to Unity and the fake save station was a nice change of pace.
Overall, it's a cool little game, and I've had fun playing it.