Is it legal to create a computer game version of SuDoku (I know there
are already many in the market)? Do you need to get the rights to it
from the Japanese company that invented it or can anyone produce a
version and call it SuDoku.

Hello mobileman1234,

The disclaimer at the bottom of the page states that answers and
comments provided on Google Answers are general information, and are
not intended to substitute for informed professional legal advice.  If
you need a professional legal opinion, you should contact an attorney.

If you search for the trademark "sudoku" on the United States Patent
and Trademark Office (USPTO) web site, you'll find that there are
recent, pending applications for "SUDOKU" (serial number 78658217) and
"SUDOKU DELUXE" (serial number 78653266) in categories such as
"computer game programs."  You can find some details about the
application by clicking the serial number, word mark, or "Live," and
further details by clicking "TARR."

"Trademark Electronic Search System(Tess)"
USPTO
http://tess2.uspto.gov/bin/gate.exe?f=tess&state=9htu9f.1.1
["New User Form Search (Basic)":
http://tess2.uspto.gov/bin/gate.exe?f=searchss&state=9htu9f.1.1 ]

The USPTO's FAQ on trademarks states:

"Federal registration is not required to establish rights in a
trademark. Common law rights arise from actual use of a mark. 
Generally, the first to either use a mark in commerce or file an
intent to use application with the Patent and Trademark Office has the
ultimate right to use and registration."

"Trademark FAQ -- What are common law rights?"
USPTO
http://www.uspto.gov/web/offices/tac/tmfaq.htm#Search005

Another USPTO document notes:

"Trademark rights may be used to prevent others from using a
confusingly similar mark, but not to prevent others from making the
same goods or from selling the same goods or services under a clearly
different mark."

"What Are Patents, Trademarks, Servicemarks, and Copyrights?" [under
"What Is a Trademark or Servicemark?"]
USPTO
http://www.uspto.gov/web/offices/pac/doc/general/whatis.htm

I did not find a copyright registration for SuDoku products at the
U.S. Copyright Office.  (Of course, that doesn't necessarily mean that
a registration hasn't been or won't be filed, under this name or a
different name.)

"Copyright Catalog: Books, Music, etc." [Combined Search for: sudoku]
U.S. Copyright Office
http://www.copyright.gov/records/cohm.html

The U.S. Copyright Office states that:

"No publication or registration or other action in the Copyright
Office is required to secure copyright.  ...  There are, however,
certain definite advantages to registration."  Thus, I presume that
the trademark owner will seek to register a copyright for its
products, if it hasn't done so already.

"Copyright Basics" (Circular 1, September 2000) -- "How to Secure a Copyright"
U.S. Copyright Office
http://www.copyright.gov/circs/circ1.html#hsc

See also:

"Copyright Basics" (Circular 1, September 2000) -- "Copyright Registration"
U.S. Copyright Office
http://www.copyright.gov/circs/circ1.html#cr

- justaskscott


Search strategy --

Browsed web sites of USPTO and U.S. Copyright Office

Hi form the UK

Having got hooked on Sudoku this summer, I'm very interested in the whole subject.

I've seen loads of freeware / shareware programs of Sudoku and
although they may actually be called something slightly different they
are all Sudoku. It's very confusing.

Did you ever resolve your question ? Have you released your version of
Sudoku, I'd be very interested if you have.

Many thanks
Steve

What about a patent?  Can you get a patent of a new version that is a
significant improvement?