graspee: I don't see why they had to change the name when it was named before the WoW expansion. There's not even any confusion: it's not called simply "Cataclysm" but "Homeworld: Cataclysm".
I wish I hadn't recently spent money on Blizzard stuff now.
Shukaku: Legal issues I'm afraid, forced their hand. Blizzard copyrighted the word "Cataclysm", so it cannot be used anywhere except in Blizzard approved content.
I really do not think that is correct...;) Remember when Apple tried to get "Apple" trademarked, and failed? Blizzard could copyright/Trademark, "World of Warcraft: Cataclysm" but not the world "cataclysm" by itself of course. I think maybe perhaps they wanted to give it a more recent name--Homeworld was not re-released as "Homeworld," it was released as "Homeworld Remastered," etc. You cannot copyright nor can you trademark common English words used in the vernacular of the everyday language.
For instance, while you cannot copyright/trademark the word "blue", you could copyright "Forenza 3: Blue" for a game, or a book or a movie. They could have called it "Homeworld: Cataclysm Remastered" without a legal problem--but it's possible that Blizzard would have sued them anyway and forced an expensive fight even though Blizzard would have lost (as the two games are not remotely similar and would never have been confused with each other.) By calling it "Emergence" while explaining that it is actually Cataclysm Remastered, they avoid even the possibility of a suit from Blizzard over the name. Even though Blizzard can never, ever copyright or trademark "Cataclysm" in and of itself, that won't stop Blizzard from suing anyone who uses the word in a game title, if Blizzard feels like it. You can sue anyone for anything, unfortunately, regardless of how frivolous that suit may be. Companies give in because sometimes it is easier and simpler, especially if the company suing you has a lot more money than you do.
Apple, for instance, even back when it was Apple Computer, routinely sued small companies all the time and won often by default because the small companies/individuals had no money to fight the lawsuits. When Apple sued Samsung, I recall, one of the dumbest things Apple alleged is that customers who walked into an Apple store and saw the word Apple printed on the phone or by the logo, might think they were buying a Samsung phone...;) Or vice-versa, that someone walking into a Samsung store and looking at a phone that had Samsung printed on it might think he was looking at an Apple phone, etc. Ridiculous--that one is still in the courts, IIRC--Apple's judgments being reduced every time it goes back...;)
The laws in the states should change so that the loser in any civil lawsuit is forced to shoulder the burden of all attorney's fees incurred by the winner--that would stop many of these specious lawsuits against smaller companies. But not all of them--as the big, monied companies will not hesitate to sue the small fry *anyway*...
Anyway, that's the way I understand these issues...not that it really matters much at this stage...;)