|License||Proprietary; free to play|
Back in 1980 Cinematronics released an arcade game that, although not well known these days, was to prove hugely influential as the inspiration for Yars' Revenge on the Atari 2600. That game was Star Castle.
Your mission is to use your spaceship to shoot through the rings of shields protecting the rotating alient turret in the centre of the screen, and ultimately destroy that turret. Be careful though: the turret fires deadly energy balls, and can dispatch mines that will hunt you down and destroy your ship on contact. As the game progresses the levels get harder and harder, until you can barely keep up with the action. Only those with the quickest reactions will prevail.
Star Citadel is a modern take on Star Castle that will run in any recent mainstream web browser, and on recent releases of iOS and Android.