This is a game I am very torn about. Its one of the most polished indie games I owned and among the most well thought out 2d metroidvania games I have played. It has a great soundtrack and overall great sounds and voice acting and a solid story. Most things about this game just feel right but yet I have a hard time loving the game. Its addictive and hard to put away but might have been its underwater setting or main character that simply didn't work for me fully. I still think its a game everyone should at least try since if this is the kind of game you'd like it might be among the better gaming experiences in its genre.

The achievements follow the design of the game and are a lot about exploring and experiencing as much of the game as possible along with the common progression stuff. The two big achievements you need to keep in mind is the achievement for exploring all areas of the game and learning all recipes of the game. I'd recommend working on both from the start since otherwise you will be on a very long hunt at the end of the game to figure out what you missed (I did this, and it took me ages to narrow down what I needed).

Time to 100%: 15-20 hours

Aquaria is an amazing game, with beautiful artwork and music. The game is open, an experience you have as the story unfolds, rather than a progression of objectives that take you from point A to point B. The variety of activities and obstacles rings with that Metroid-vania classic feel, but you feel infinitely more free as you swim through a massive, oceanic world. Peppered throughout the enveloping environment are momentary cutscenes, largely untouched by narration or dialogue, that make for some of those ecstatic moments in gaming you live for.

Aquaria is one of the 2 games that spawned the indie genre back in 2007, it's sad it doesn't receive the attention (not as much as its counterpart Braid, anyway) it deserves though.

Pros:
Attention to detail
huge open world to explore
many secrets and treasures to discover
Majestic soundtrack
No handholding

Cons:
Finding where to go next or how to interact with objects/creatures can be a little vague at times (reminiscent of Ecco the Dolphin)
A few random crashes

Last but not least Aquaria is advertised as a "Metroidvania" type of game. Well, to be more accurate, it's Super Metroid reborn!!

Surprisingly good for a 7 year old Indie game. Very relaxing, interesting atmosphere and great music.

This game employs the so called "metroidvania" style of gameplay. That means you are free to roam around, but full exploration is only possible through finding upgrades that will allow you to get through certain obstacles that you couldn't before. The world is immense and there's a lot of backtracking to be done but the gorgeous graphics and different themed locations, not to mention the masterfully crafted soundtrack, do a great job at minimizing the tediousness. The upgrades themselves are pretty cool, though their usefulness vary and some feel underwhelming compared to others, even though the same can be said about the parent games of this genre. The controls are very responsive and all of the character's moves can be done with just the mouse if the player so desires. The combat is very energetic and being underwater allows for a ton of dodging, which you will have to become proficient at to get through this game since the screen can get quite busy with projectiles and enemies at times and your character can't take a lot of beating. This difficulty can be severely mitigated by the ability to cook many kinds of food, as several of them heal your character, increase her defense capabilities, or even both depending on the kind of food itself. There is a plethora of secrets to find (some useful like cooking recipes and pets that will fight for you, some just aesthetic like costumes), the rarest of them often protected by optional bosses, all of which will very well push the playtime past 15 hours if pursued at a normal pace.
Overall it's an excellent game in my opinion; It hits the right notes in all technical aspects, has an interesting story and a very satisfying amount of exploration and content. Greatly recommended!