Drop charges around a field maze and shape the force landscape so a launched particle arcs cleanly to the goal.
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How to play
Each level has a test particle, a goal, and walls. You place point charges to sculpt the field, then launch the particle and watch it accelerate under real Coulomb attraction and repulsion. On magnetic levels a uniform field curves the trajectory into arcs.
Choose a positive or negative charge with the sign selector.
Click in the field to place charges where they'll steer the particle.
Press Launch to release the test particle and watch it respond to the forces.
Thread the particle through the gaps to the goal to clear the level.
Controls
Desktop: pick + or - charge, click the field to place charges, click Launch; switch Daily/Practice in the bar.
Phone & tablet: tap to set the sign and tap the field to place charges, fully touch-friendly.
Tips & strategy
Opposite charges pull and like charges push, place a charge past the goal to draw the particle in, or behind a wall to deflect it.
Charge force falls off sharply with distance, so a charge nudged closer has an outsized effect.
On magnetic levels, plan for a circular arc rather than a straight shot and set up the radius that threads the gap.
What you'll learn
Lodestone is a hands-on electromagnetism sandbox where the puzzle is engineering a field rather than aiming a shot.
For parents & teachers: engineering electromagnetic fields.
Origins
Placing point charges to sculpt a field and launching a test particle under real Coulomb attraction is electrostatics as level design.
Steering by field rather than by force applied directly is the original mechanic.
A field is the right abstraction and this shows why. Coulomb's law falls off with the square of distance, so a charge's influence is intensely local and then almost nothing — which means shaping a trajectory is a matter of placement rather than strength.
About Lodestone
Lodestone is a hands-on electromagnetism sandbox where the puzzle is engineering a field rather than aiming a shot. It's an original, free browser game integrating genuine Coulomb and Lorentz physics, with daily and practice runs.
A free, original browser game on PlayPendium. No download, no install.
