Every time I make a new game this comes up. Your game's name is a trademark, and in a sad twist of events your chosen name is someone else's trademark! :(
For US check the trademark database (TESS) and see if they have even bothered to trademark into more than just music and extended their trademark to cover digital entertainment markets. Take some time to look at companies trademarks (e.g., Rovio's Angry Birds) and compare it with other popular titles. The grey areas crop up quick. The language and breadth of a trademark's declared written language matters. There is all kinds of fair use laws too. Infringement on an artists likeness, is it parody? How much likeness is allowed. I read about these going both ways all the time... and I am drawing a blank on an example on good examples both ways! (help! anyone?) Weird Al comes to mind, but he asks artists if they mind... Although even that can get messy in the telephone game world of he said she said (for the record I really like Mr. Yankovich's response to all that drama.)
So where to start. I promised an entry point... I always check out TESS http://www.uspto.gov/trademarks/index.jsp
It costs a bit of money to get trademark, and more so if you pay a lawyer to go research a conflict. Then once you have it you must defend it to keep it. That is why any mention/use of another's trademark is frequently met with swift responses oftentimes. Then there is parody, even that is a minefield of potential litigation to navigate... :P
Even before you acquire the full legal trademark a step, that I am aware of, is to start MARKING your stuff (tm), You see that little TM everywhere... That is the warning sign that you intend to or have trademarked what is marked. And it more than just names. It gets complicated rather quickly... too quickly...
I am not familiar with the governing agencies outside the US and I must also declare IANAL (I am not a lawyer), but I know a good one who has done me right, steered me clear, and has a background in patent and dabbled in trademark law. If you get serious, consider a lawyer, it might lead to something (not just fees paid out!) We recently had to defend a property that someone tried to trademark (and claimed WE infringed on) only to discover they had little ground because we had been in market on the App store a year before they even announced development (luckily for all we worked it out and were happy to be compensated to give up rights to the name so they could use it. great game too! Keeping our name was likely to occur if we fought it, and royally screwing them. I hope we get treated the same way when we are big and screw up with a trademark snafu (or in this case a lawyer team screwed up!)
I'll ask my lawyer friend if they want to be publicly named before doing giving him a plug... I think they like working in the shadows... That is a lawyer thing isn't it?