Remember the classic game Depth Charge ? Well its origins are pretty old, going back some 30 years are so. To get you up to speed, its a game of cat and mouse between you (a Battleship) and a load of U-Boats / Subs - trying your best to avoid / destroy them using a Depth Charge or from the subs, torpedoes. 

This game has a long history, going back to the Intelivision and Apple II systems in the 70s, then later onto the mighty Commodore 64 and then Amiga - which this free port comes from. 

Game mechanics are pretty simple and easy to use, left - right - fire and that's about Depthcharge has no special permissions to run either and best of all its free from the Play Store here.

Grab it.