Developer posts and news about this game.
I have added a new option to the customize marble texture dialog which allows the player to add a custom texture. This texture must be stored as a .png file with a size of 256x128 pixels. The number section is still auto-generated.
MarbleGP does now support Track Packs which can be created with the MarbleGP Track Editor (in development)
I have fixed a problem which was reported several times: the shaders for the in-game graphics did not work on AMD cards. This is fixed with the latest update (I hope)
Yesterday I realized that the network gaming is not working at all. This is now fixed, the feature does now work (but needs a stable network connection)