Kepler: Orbital Slingshot — gravity in the browser
«Kepler» is a physics puzzle where you launch a probe across a field of attracting
and repelling bodies and guide it to the exit portal. The task looks easy until you
remember that the trajectory bends around every planet: the probe does not fly
straight, it follows a curve you have to plan in advance.
Why it is interesting
Under the hood sits a simplified law of universal gravitation: each body creates an
acceleration inversely proportional to the square of the distance. Several bodies at
once, and you get a planning problem close to real satellite ballistics. The same
level can be solved in a dozen ways: a straight shot, a gravity loop around a
planet, or a ricochet off antimatter.
What a level is made of
- A launcher where the probe starts.
- Planets (blue) pull, antimatter (pink) pushes away.
- Orbs are yellow pickups worth points.
- Asteroids and planet cores destroy the probe.
- The green portal is the level goal.
Strategy
Score grows from collected orbs and from unused launches. So it pays to clear a
level in a single precise shot, using a planet as a sling: swing the probe around it
and it flies off in the right direction with extra speed. Repelling bodies act like
invisible walls — handy for steering the probe away from danger.
Six levels ramp up gradually: from a pure straight shot to three bodies and an
asteroid field. Try to clear each one with the fewest launches.