First of all, I will say this:
鈥淟ET THERE BE CLONE!鈥
Why?
Because I have seen too much in my life that the act of copying (or borrowing the idea) lead to many great products in their future.聽 I鈥檒l give an example later.
Another reason is, it will promote the genre heavily.
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Some will say: 鈥淏UT CLONING IS NOT THE SAME AS COPYING鈥
Exactly!聽 Clone in terms of genetic biology science refers to a word of identical EXACT replica.聽 So if you really never find a game that EXACTLY the same, why do all people keep using this term as a word to represent someone who copy some aspect of game to develop a new one?聽 They are not doing the real cloning in this term.聽 Splices point of view explain it, so I won鈥檛 cover it anymore in here.聽 Go read it here.
Yes, I understand there are so many terms out there for clone鈥檚 meanings.聽 In this case, from this point onward, I will use this terms as the 鈥榰sual鈥 meaning tendency, that a game is similar to other in many many ways.
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Genre Promotion
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Before I explain my first reason to support the clone, I will go to the second: clone war will promote the genre heavily.聽 If the genre become alive, it will attract many people or companies to consider penetrating the genre鈥檚 market.聽 And it will force them to be more creative if they don鈥檛 want to die.聽 So it is good.
聽VS 
Most people in the world, know these 2 brands: Coca Cola and Pepsi Cola.聽 And cola genre is really getting promoted heavily during cola war.聽 Now if we refer to Maple Story vs Wind Slayer, I don鈥檛 even consider to try Wind Slayer, but because of this clone war, I am 鈥榝orced鈥 to download it.
聽VS 
Some people complaining about why we are comparing titles in the same genre.聽 I have to say IT IS NORMAL to compare.聽 Maybe it will be a neverending clone war.聽 But it鈥檚 completely OK and healthy!聽 It promote the genre.聽
Face it: people compare many thing!聽 I found a debate about who鈥檚 the greatest in soccer, Pele vs Maradona.聽 I found a war about operating system in a seminar, Windows vs Linux.聽 I found a site that has a neverending topic about who鈥檚 the best in console, PS3 vs XBOX360 vs WII.聽 And they are all have their own valid argument.聽 So it鈥檚 basically a neverending war.聽 But once again, it is normal.聽 In the end, the market will decide the product鈥檚 life.
As for the MMOGs clone war, it will force developer to think creatively about how to differentiate their product.聽 When I review and compare Ghost with Maple, people start complaining about why do I have to compare.聽 I have to say, I have to!聽 Besides, it is an input for developers too.聽 If there鈥檚 clone war, let it be folks.聽 People has right to say about their opinion.
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Embryo
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Post World War II, Japanese, the defeated party, suffered a devastating result.聽 Their industries ruined.聽 They barely can develop anything.聽 But they eventually started it 鈥 by copying technology from the more advanced country.聽 They earned the title as copycat nation.聽 BUT, 50 years later, they are no longer held the title.聽 Maybe China does now.聽 Japanese companies become international companies, as we know many of them, even in the world of game: Sony, Nintendo, SEGA, Square Enix.聽 They taught us one thing, it is OK to START WITH copying or cloning, BUT proceed them by adding CREATIVITY and NEW features.
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In the world of game, do you find similarities between Disciple and Heroes of Might and Magic?聽 But they both earn popularity and produce sequels that worth to play.聽 Dune II with Command and Conquer?聽 I believe the world well known title of RTS also copied some features from them, including Warcraft series.聽 And Warcraft is one hell of the great game series I鈥檝e ever played.聽 They start with copy and similarities.聽 But that act is an embryo of many great games!
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I believe the world of MMOGs will apply the same rule.聽 Clone it in some ways, add new features, and someday, there will be great games.聽 Do you think that World of Warcraft is an all fully NEW features game? 聽Yes they are great at some aspect but that doesn鈥檛 mean they didn鈥檛 copy some features from other game.聽 Have you read Paradox article explaining that Ghost Online was come first but nobody called Maple as clone of Ghost?聽聽 So even if they did clone Ghost, you鈥檝e seen a prove that clone can be a popular (or for some people, great) game.
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Well, the MMOGs industries will full by 鈥淎ttack of The Clones鈥.聽 But this may rise a 鈥New Hope鈥.聽 Because it will force the 鈥淥ld Title or Company Strikes Back鈥 or 聽we will see the 鈥淩eturn of A More Creative Clone Game鈥.聽 Do not underestimate the power of the clone.