Since you are already going the unofficial route, why not enhance the game? Here are the top mods compatible with v2.1 repacks:

To install these mods, download the .dll files and place them in the GeometryDash/Resources folder, then run the game via Injector.exe (if provided).

Geometry Dash is a popular rhythm-platformer with a passionate modding and repack community. References to a “v21 repack” usually mean an unofficial, repackaged version of the game—often modified to include unlocked features, mods, or bundled custom levels. Below is a concise, balanced blog-style examination you can publish.

During the 2.1 era, the official Geometry Dash servers often underwent maintenance or suffered from DDoS attacks. Modified repacks often included server bypasses or redirected the game to private servers, allowing players to load custom levels when the official servers were down.