With this month finally seeing the release of No Man's Sky, in which players can investigate and explore a huge universe full of diverse planets, I couldn't help but be reminded that although outer space has always held a fascination for many, there's another largely unexplored area much closer to home – the ocean. Although water makes up about 70% of Earth's surface, it is estimated that humans have only explored around 5% of the seabed. Aquatic legends such as Atlantis, the Bermuda triangle, and the disappearance of the USS Scorpion in 1968 have captured the imaginations of many a budding oceanographer, and as such the depths of the sea are an unknown region still ripe for mythologizing – which is exactly what Abzu does, in the first release from Giant Squid software. Directed by Matt Nava, who worked as art director on Journey and Flower for thatgamecompany, the style is instantly reminiscent of his previous work, with players taking control of a stylised'Diver' character. Dropped into the ocean with little explanation, the first thing you notice is how - no matter how long you spend underwater - there's no air gauge to run out.