This game tries to be Metroidvania (with the map, ability gating progression, and weapon upgrade) but fail pretty hard. So if you're looking for a good Metroidvania, this ain't it.

While the map feels open, it's mostly a linear game with objection marker telling you where to go. Even if you try to explore you're most likely going to be punished anyway because 90% of the off beaten path only contains healing/ammo item (which you don't really need), the 10% does contains weapon upgrade.
The ability gate is fine, but nothing that change your gameplay, it's mostly keycard, tools to open door, tool to light up room, and tool to turn off deadly turret.
There is one annoying "upgrade", which is a flamethrower, you need it to open some doors. But it counts as a weapon, which can only be exchanged in a save room. So I do have to backtrack a few time just to open door, because I was not carrying a flamethrower. This could've been easily solved if you just bring every weapon with you.

Still a really good 2D side-scroller game though, fun characters, decent story, combat is a bit janky, but serviceable.