Orbit — free browser game

You're planning a space mission. Your satellite will start moving from the left edge at a fixed speed and heading; you, meanwhile, have to place the gravity wells on the map BEFORE launching. You drop a well by clicking or tapping an empty spot (the counter at the bottom shows how many wells you have left); clicking on an existing well takes it back. When you're ready, press the 'Launch' button or tap the Space key. The satellite goes into free fall, and each well applies a continuous force on it following the inverse-square law (pulled in when near, weakening at a distance); the total vector bends the satellite's trajectory. If you can pass it through the target ring you win the level and advance to the next, more constrained one. If the satellite leaves the screen, crashes into the core of a well, or hits the red asteroid, the level resets — but your well placement stays, so you only need to fine-tune. Strategy: if you put a well too close to the satellite's path it falls into it; put it too far away and the effect isn't enough. First bend the general heading with a distant, weak well, then make the final turn with a strong well near the target. The faint trail of the orbit is drawn during the launch; reading the trail, nudging the well by a few pixels on your next attempt is usually enough.