This game is similar to Super Metroid (SNES) and several Castle Vania titles. In terms of genre, it is also compareable to Zelda, Demon's Crest or Mega Man.
You are a bounty hunter on a space station, running around and shooting stuff, discovering secrets and fullfilling objectives. You will unlock new abilities and weapons in order to access previously locked or hidden areas and you will also increase your combat capabilities along the way.
NOTE: I will not give an overall score because everyone is looking for different qualities in games.
Story / Feel:
No spoilers except things you find out very early on anyway. Also not spoilering the intro cinematic.
The setting is a space station which has several habitats for breeding different life forms. You will visit each of those multiple times, as well as going through techincal areas. Some story elements will change the habitats (not only optically but also in terms of gameplay), so overall this results in a nice variety of scenery.
In contrast to Super Metroid, there is actually some dialogue (and monologue) now: an AI relays HQ orders to you. The story develops nicely and I especially love how they include gameplay elements (such as upgrades or your characters weaknesses and strengths) into the actual story. The story connects to previous Metroid titles while introducing a new, well thought-out overall enemy that is cleverly designed to deliver reasons for several gameplay elements.
Sadly, there is no voice-acting (with very few exceptions) but 90% of the music is good and fitting.
The game occasionaly breaks it's own thought-to-be-rules which means you are always in for a surprise. Combined with the interesting and sometimes scary enemy/environment design, this delivers a great atmosphere of exploring the dangerous unknown with some survival elements here and there.
As mentioned there are tons of tiny little secrets all around. Some of which you will accidently stumble into because of great level design (you might accidently bump into them and they are often on your way of progression), others absolutely make you go "whoa! i could have so easily missed that!". most importantly, these secrets only give you more ammo and health so you will not miss out on much game content if you overlook something.
There are quite some bosses which usually require a little bit of thinking.
Gameplay / Controls:
Regarding controls, the only annoyance i found is that you need to hold an extra button to fire diagonally (unless you are moving). Other than that, things are fine. Compared to Super Metroid, they simplified the controls a bit: there is only 1 type of missle now (that can be upgraded several times though) and the need to cycle through your equipment has been eliminated. Sadly, this limits your combat choices to shooting or charging your weapon, possible dropping a powerbomb. You can basically do everything you could do in Super Metroid and they added the possibility to automatically grab onto ledges which turns out to be a great mechanic.
If you are a completionist (trying to get 100% of all items), things can get a quite tedious and you might also come across secrets that are ment for later.
Other than that, it's another nice action rpg gameplay wise although it could offer more different ways to fight.
Replayability / Secrets:
As mentioned, there are tons of little secrets to find so it's definately worth replaying. The story twists might be gone, but the atmosphere mostly remains if it's been a while since you last played it.