Insomniac Games has certainly been keeping itself busy lately. The studio has been launching game after game over the last couple of years, all of them of the quality you'd expect, and it seems it's prepared to tackle almost anything – big or small. Nestled in-between its successful re-imagining of the first Ratchet & Clank and its forthcoming Spider-Man title is Song of the Deep. While it may not have the bombast and the humour of Insomniac's other games, this 2D Metroidvania more than makes up for it with bucket-loads of charm.

The story follows Merryn, a young girl whose fisherman father doesn't come home one night. Following a vision of him trapped beneath the sea, she sets about finding him, building a small, rickety submarine from spare parts and diving into the big blue. It's a simple premise, but it's eloquently told, written well, and narrated perfectly.

The first thing that hits you is the beautiful art style, with cut-scenes that look like illustrations from a children's book, and a colourful, detailed underwater environment in-game for you to discover. It's all extremely well realised, the ocean full of life and mystery, with a superb melancholy soundtrack creating a sometimes haunting, sometimes joyful atmosphere. Sadly, the technical performance doesn't quite match up to the presentation, with frequent framerate dips when there's too much action. It also pauses for a second each time that you hit a save point, which we didn't find to be much of a problem, but it could be smoother.

You begin the game in the safe shallows, with no abilities beyond moving through the water. It doesn't take long for you to find the Magnetic Claw, however, which is your most versatile and useful equipment throughout the game. Not only can it be used to grab and throw things, but it's also handy in combat. After a little while, you're able to explore more freely. There's always a marker on your map showing you where to go next, but you can safely ignore it and wander around as far as you like. With this being a Metroidvania, though, expect a lot of gated areas and seemingly impossible-to-collect items along the way.

It never gets too complex, and new skills are spread out nicely. There will be doors or objects you can't open up until near the end of the 8-hour adventure. Exploration is highly encouraged, and it pays to backtrack to cordoned off locations; not only will you find treasure and health/energy upgrades for your sub, but there are even new abilities and whole new puzzle rooms to solve. The surprisingly big map is intelligently laid out and, because of the lovely art, it's one that you won't mind filling in.

However, enemies are numerous, so you'll spend as much of your time attacking all manner of nautical nasties as you will exploring. Many of the submarine's abilities double up as both combat options and navigational tools, so you'll always be well equipped to tackle them head on. As you progress, you'll gain access to various torpedoes – they'll all deal damage to your foes but they have different effects. For example, the ice missiles will slow down your enemies, while the magma ones leave a fiery cloud that chips away at their health. Fighting the fishy fiends is often pretty haphazard and directionless, with the floaty controls sometimes making it hard to evade their attacks. The game can rely too heavily on combat as well, sometimes locking you into rooms until you've bested enough baddies. These forced fights are probably the weakest aspect of the game, alongside some anticlimactic boss battles.

The puzzles fare slightly better. There aren't any true head scratchers to speak of, but they're entertaining nonetheless. A particular highlight about half-way through the game is a lengthy puzzle in which you must guide a beam of light all the way to the top of a tower, using mirrors to reflect it into switches. Often the puzzles are of the 'doors and switches' variety, some requiring you to rebuild statues to progress, and others that ask you to navigate large objects onto pressure pads. These are probably the trickiest puzzles, but not for the right reasons. Shunting heavy objects around with the nose of your submarine doesn't sound like a big deal, but in practice it will take you multiple tries due to the nature of the game's physics. The floaty, weighty controls make contextual sense, but they're not good at points where precision is key, resulting in many dropped or exploded objects, and your patience wearing thin.

Conclusion

Song of the Deep has a big heart, and is a fun, uncomplicated game that players of all ages will enjoy. The abilities are fun to use, the gameplay is mostly solid, and the presentation really won us over. Exploring this lush seascape, solving simple puzzles, and experiencing the sweet story – this is where the game excels. It contains most of the established rules and trappings of a Metroidvania, and is one of the easier games that we've played recently, but this isn't necessarily a bad thing. Sometimes, it's nice to play a game that doesn't ask too much of you, one that allows you to relax and simply enjoy being in its world. If you can forgive its technical hiccups and learn to adapt to its loose controls, you'll have a whale of a time.