There actually is a way to play this as of recently! Couldn't believe it myself, quite frankly.
Though you have to keep in mind you won't have access to the Leaderboards and your progress isn't going to be saved, that is all the experience you attain and skills and auras. Times and collected tokens will be saved in your computer, but please don't quote me on the tokens as I haven't tested them yet.
If you want to play MBF again, then make sure you have the latest Marble Blast Launcher version and do the following steps:
Click whatever launcher appears at the top (PlatinumQuest Launcher will likely be your only option), then click Configure Mods.
A new window (Manage Marble Blast Mods) with all of your installed mods will pop up. At the bottom of it you will see a text box and there you should copy and paste the following URL:
...to let the server know what to download (In this case that is Marble Blast Fubar BETA 51020).
At the end you should click Add Mod, and that's really it. Close the window and go back to the main window you started with and choose the Marble Blast Fubar Launcher, which should be your option by then.