What causes radial planet gravity orbit instability?

Explicit Euler integration of an inverse-distance gravity force adds energy over each large timestep, so orbits decay inward or expand outward instead of staying stable.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Radial Planet Gravity Orbit Instability

Quick answer: Use a smaller fixed timestep, a symplectic (semi-implicit) integrator, and apply gravity as acceleration, so orbital energy is conserved and bodies hold their paths.

Planet gravity that should produce clean orbits instead sees moons spiral into the surface or drift off into space. That is integration error accumulating energy each step. Here is how to fix it.

How to fix it

1. Integrate semi-implicitly

Update velocity from the gravity acceleration first, then update position using the new velocity (semi-implicit Euler). This symplectic scheme conserves orbital energy far better than naive Euler.

2. Shrink the timestep

Reduce the fixed physics timestep so each gravity sample over a curved path introduces less error; tight orbits need finer steps than loose ones.

3. Apply gravity as acceleration

Compute g = G * M / r^2 toward the planet center and apply it with ForceMode.Acceleration so mass cancels and every body follows the same trajectory regardless of weight.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.