Nice little retro game!
It's a little bit basic overall and feels like a 'my first action platformer' game from a first-timer dev, but I don't want to be too down on it because it actually does a lot of things very well in terms of design:
For one, it starts out strong by immediately getting the player into the action and introducing some cool mechanics like gravity switching.
Next, the game kept my interest by having each level add something fresh and distinct to the mix, be it a new mechanic, tileset, obstacles and so on, alongside mixing it all together with tricky combinations.
Finally, it all ends with a good ol' boss fight which has a decent attack pattern and an enrage phase!
So yeah, it's not necessarily anything groundbreaking or truly interesting, but it was a fun short romp and I think it displayed some good design fundamentals that a lot of other games in this ilk get wrong, particularly from first-timers! And yeah, it's nice to see more appreciation for Metal Storm: I was a latecomer to that game myself!