The world is underwater, and humanity is locked in a fierce battle for survival. You might think this is a story of a post-climate-change future — but then that doesn’t explain the aliens. This is Sea Fortress, the new strategic action game from publisher IGG of Lords Mobile and Castle Clash fame. Earlier this year, we announced its pre-registration. Now this open-world, real-time MMO is making its maiden voyage, and you’ve get a free ticket to ride.

Sea Fortress throws you in the deep end amidst other players and extra-terrestrial foes — called cybers. Your best bet for survival is to build the strongest, scariest fleet of battleships, submarines, destroyers and aircraft carriers you can, customising them as you go. But it isn’t all about the firepower; it’s also about forging alliances with other players, growing your territory, gathering resources and researching technology. You’ll also have the chance to recruit talented war heroes to put at the helm, each with their own strengths and weaknesses to consider.

As well as the day-to-day multiplayer battles, Sea Fortress features an exciting single-player campaign to work through — a great opportunity to take a breather from the competition, test your skills, then return to the global PvP arena better than ever. You can also head out on monster hunts, taking down the cybers lurking in the high seas.

Base building, strategising, battleship customising and much more awaits in Sea Fortress, available now on Android and iOS.