Level showcased here is Supersonic

Cube, ship, ball physics almost perfect at this point. The other gamemodes should be easy

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TLDR: I’ve been working on a Geometry Dash simulator that tries to match the real game’s physics tick-for-tick, not just approximate the movement visually.

The current focus has been ship mode, because tiny differences in ship physics snowball really fast. I’m comparing my simulator against a canonical tick log from Supersonic with exact `x`, `y`, and click state data, then generating my own tick log and diffing the two traces.

So far I’ve been working through a bunch of subtle GD behavior:

* Starting speed from the level header, so Supersonic actually starts at the correct 2x speed.
* Ship gravity acceleration and release/hold behavior.
* Gravity portal behavior for ship mode.
* Inverted ship gravity, where release must accelerate upward after a gravity flip.
* Rotated ship hitboxes for collision.
* Input phase alignment against the canonical click trace.

The coolest part is that the visual path is now very close to the real trace. I’m overlaying the canonical path against the simulated one, and the early ship section is down to small-unit differences instead of being completely wrong.

There’s still more to do. I don’t want this to be “close enough”; the goal is exact canon parity. Right now the remaining error seems to come from some missing global velocity/frame-scale detail or an incomplete port of one of GD’s internal ship state predicates.

But it’s finally at the point where the simulator looks like it’s actually following Geometry Dash physics instead of just imitating them.

If anyone has experience with GD decomp/OpenGD/GDP ship physics, especially `playerIsFallingBugged`, `flipMod`, or ship velocity scaling, I’d love to compare notes.

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Eventually I will make a level difficulty determination sim to settle debates between which level is harder.

GD Simulator w/ Accurate Physics - Part 2