Client Side Modding is possible in Nin Online. Many things can be changed but ill just start off with music, as it is the easiest! First things first get your music, In this tutorial i picked "Wind" Go to http://mp3skull.com/mp3/naruto_theme_wind.html to download "Wind" When you reach the page right click and of the links that say "Download" and press "save link as" Then save it to a safe place on your computer. Next step open up Audacity or any other program that can export a mp3 or any normal sound file and change its file type. So open up your song in Audacity or the program you selected, then export it as a .ogg. Name it "Menu" then save it to a safe place. Then go to C:Program Files (x86)Nin Onlineclientdata filesmusic and place the song called "Menu" you just created in that there a box will pop up click "copy and replace" Now if you start Nin Online with the launcher it will delete your custom song so go to C:Program Files (x86)Nin Onlineclient and double click "Nin Online" Nin Online will now start up with your custom song and it will loop Happy times! Well done if they are any problems write a comment or private message me I am willing to help anyone who seeks help. I also recommend you copy the original menu.ogg and place it somewhere safe just in case you do not desire the menu song you selected anymore you can revert back to the old menu song.