I will group it into categories.
Graphics:
They are looking nice. Altought some of them looks like they were taken from Metroid or copied with some changes . Also some of the sprites are just lazy. Like the diversity among enemies is made by just scaling them, which as I said is lazy and looks bad with the rest of sprites, because of that scaled up pixels. Lava's animation (idk if there are other liquids. I didn't finish this game) are also lazy and are looking bad with other sprites as it's just a simple wave animation with deforming pixels.
Enemies:
They're just a copy of enemies from Metroid with custom skins. Like those green orbs, who are clearly Metroids, they even can also be defeated only with rockets.
Music:
There is none. Except for one, when you are picking up an item.
Sounds:
Okay, enough. Generic.
Mechanics and bugs:
I don't like that ammo and energy drops randomly from enemies and not always, like in Metroid. This isn't a good way to add to difficulty of the game. Also it seems random that you can or cannot jump where you should be able to jump.
You can glitch some or most doors in this game, but opening them, entering them, and then immediately coming back. After that you can enter those doors without shooting them. Also if you come with enemies from one screen to another, they will come with you.
Overall rate 3,5/10.