OpenTyrian

OpenTyrian is a free and open-source version of the classic Tyrian, a SHMUP (shoot 'em up) that puts you behind the controls of a spaceship. Your goal is to advance though a series of levels full of enemies and dangers while shooting at basically everything that moves.

The main gameplay is typical for the genre: your spaceship is located at the bottom of the screen and your enemies come at you from above and the sides. All the movements and shots are made using touch controls. You have to have some skill if you want to dodge the hundreds of shots coming at you all at once.

The game includes five episodes, each with its own final boss and tons of different weapons for you to combine (you almost always have two at a time). That's all in story mode, of course. You also have an arcade mode where you can complete nonstop missions, without following any sort of story line.

OpenTyrian is an excellent port for Android of an awesome PC classic. The controls could be better, but in general, it's a really enjoyable game.