Every time I play Rumble Fighter it continuously keeps telling me that there's a game hack detected even though I have never hacked in my life. Thing is I'm really bad at this but not so bad to the point where I start hacking. If this is a bug fix it. I've even sent a ticket regarding this.
Try redownloading the game, or restarting your pc. Then stop the game from running in the background if thats whats causing it. You can do that by checking task manager.
I think this has happened to everyone at one point. Just to clarify nothing at all will happen to you for this error (like you won't get banned). You should follow @UnleashD advise and I heard that if your internet connection is slow this may also give you this error, but I don't anyone knows 100% why people get this error.
It's usually caused by a conflicting program. Any antivirus software I've had running when starting Rumble Fighter has always given me this error, so I have to disable my anti-virus when I play RF. They should fix it so that anti-virus programs can run alongside it.