Shooting games are usually a challenge of targeting your enemy accurately while they are moving around. This is complex because of the quick reflexes as well as using two sticks to navigate the 3D environments you are playing in.
Twin Stick Shooters, take this mechanic and simplify it. You view the play from above and use one stick to control movement and the other to control the direction of your bullets. This simple change (harking back to the days of Asteroids) makes the play simpler and more direct while also offering a big challenge for players.
This list includes 53 games from the last 28 years, with 192 likes. They come from a range of different genres and play-styles and are all good games if you want to shoot and move in different directions.