This just happened on BGG. I am subscribed to a roll 'n' write PnP game called Project H.U.N.T.E.R. that was meant to take part in the annual R&W contest. It is a cool-looking mech vs.monsters fight which I intended to print out and try.
The 'designer' (Soul Tech) seemed to have made quite some progress with the help of the community, made some rules editing and also produced a colour edition. It was all going well... until tonight.
Another BGG user (Tiago Junges) suddenly showed up in the thread claiming the design is actually his own. He has a Brazilian website called Coisinha Verde in which he publishes his game designs. And lo and behold, Project H.U.N.T.E.R. is in fact... Projeto Hades! The contestant apparently stole it and translated it into English.
Within minutes, the original post was deleted. The H.U.N.T.E.R. was caught.