This document attempts to document the structures of data that Geometry Dash uses to store information about the game. This is primarily intended for mod developers/hackers who want to read the executable's memory.
If you have any additional information about pointer locations or meanings, feel free to post it in the comments below.
The following data is from version 2.11, 32-bit Windows on Steam. This information will likely differ depending on the version, architecture, and platform.
This structure appears to be mirrored four bytes ahead at [[[GeometryDash.exe + 3222D0] + 164] + 228] + 600, for the second player in two-player/split mode.