There is only one file type that uses the .N-GAGE extension:
Game or application developed for the Nokia N-Gage platform; can be installed and opened on an N-Gage compatible device, such as the Nokia E and N series of phones.
N-GAGE files can be installed on a Nokia mobile phone using the Nokia Application Installer, which is part of the Nokia PC Suite. They should be placed in the \n-gage directory in order to be recognized by the phone. N-Gage games and applications can also be transferred from the phone to a PC for backup purposes.
Updated: May 21, 2012