I had the exact same problem!!! And this started recently and was like wdf??? But anyway I just fixed it today and here's how I did it..
First make sure everything is uninstall ed, like rumble fighter and the ogplanet launcher.
Then, what I did, I download the actuall rumble fighter game FIRST. Then when you download that, then try and run it, and you'll see that no files are uploading. Leave it, and then install the Ogplanet launcher. And when that happens run the launcher, and this time for some strange reason it doesnt disappear!!!! Sign in, then click play. (you will noticed rumble fighter has already been installed)
Once you click on the play button. another rumble fighter file uploader will apper, but this time you will be downloading all the updates. (For me it was like 600 something files!) then when ur updating files, then you can X out the other one that isnt doing anything. and BAM. You should be able to play
Hope this helps :D