You're an alien whose spaceship has broken down, armed only with a magnet. You work your way across the galaxy using your magnet to slingshot you from orbits surrounding the planetoids filling the many levels of Alien with a Magnet (AwaM). Throughout the game you only need one finger with no fiddly controls; you hold down on the screen to make the ship orbit around the planets, and when you have the right trajectory you take your finger off and shoot off into the next orbit and repeat. While this kind of game isn't new, there aren't many like it and none come to mind that have as much charm and enjoyable music.
The earlier levels start off introducing you to the basics of getting around and working out trajectories. After these tutorial levels the difficulty ramps up at an increasing rate. First the marshmallow boundaries are taken away to keep you from crashing. Then your ship begins to use power, so orbiting planets drains your power until you find a recharge planet. Then there are also space cannons to fire you around the map and levels with multiple exits, all the while trying to gather three green orbs and as many gems as you can. I found myself quitting in frustration a few times when levels the got harder, but I always came back to it and kept on going.
Alien with a Magnet does a lot with its simple controls and provides a good challenge. If you're looking for a puzzle game with good controls that isn't already overdone in the app store, you should check out this game. Even better it won't cost you much.