It's a faithful reproduction of the gameplay from Super Metroid and Metroid Fusion, borrowing mainly from the latter in tone with all the biological weirdness saturating the lonely alien environment. Also has a touch of BLAME, the manga, shot through in the form of entities like the huge, derelict robotic head on the cover art. The main character himself, a cagey scientist who spilled into an alternate dimension, suffers by being not as cool or iconic as Samus... but few protagonists are, and even that lends credence to how well this game's environmental design hits the right notes. The gameplay is tight in that Metroid-y way, with careful regulation of how much the player can do at a given time (barring, I have to assume, some cleverness in sequence breaking)... although I found myself frequently frustrated at the grappling hook because its short range and finicky angling made passing platforming challenges with it the biggest sticking point of the game for me. There's a substantial amount of optional pickups, but not so many that they begin to feel meaningless, including a large supply of weapons. Some of the secrets are hidden in ways that take some actual care and ingenuity to uncover. I'd say the game is exactly as long as I'd want it to be: not done too soon, but not overstaying its welcome. It's left me ready to dip back in to the optional Randomizer mode for some good old replay value.