One of my old DMs created a new gaming system. He has been rpging for years. He has played many systems and DM'ed them as well. He has come up with a new gaming system for a homebrew setting. It is more than just a bunch of house rules. He was thinking of putting it on the web but I told him there were many similarities with other systems. He said it was a combination of old and original ideas. Is this plagirism?