I just wondering that can I name my game characters on the "real" names? Is this somekind of rules or something that I cannot do that?? Example at the wrestling names, like Hulk Hogan or band names like Nirvana?
I would recommend that you consult an intellectual property attorney in your area for more information, but generally, these names are either trademarked or (in the case of an actual person's name) could be an issue due to right of publicity. To avoid any legal implications, it would be best to use names you've created rather than names of famous people, bands, etc.
Using 'real names' a such as Hulk Hogan, Marilyn Monroe, etc., will get you into trouble because in the case of living celebrities, it could be mistaken for ENDORSEMENT. Stick to parodies (Dark Helmet instead of Darth Vader), BUT REMEMBER- if it isn't a name , person, or place that you have created, someone has royalties or copyrights on it.
And they will come after you.
In fact, if it has anything to do with Disney characters, comic book characters, or anything Jim Hensen had to do with it ... believe me ... if they find something they own they will hunt it down. First you will get a 'Cease & Desist' order/request, then you will get a lawsuit. Likewise, this goes for anything controlled by a decease's estate, such as Elvis, Marilyn Monroe, etc.
It will not hurt to look up (and ask a lawyer) about what constitues 'Fair Use', and what the copyright laws say about it.
Just design your own stuff - it's easier!