There is only one file type that uses the .NGAGE extension:
N-Gage Game File
Video game written for the Nokia's N-Gage mobile gaming platform; can be played on an N-Gage phone or a Nokia smartphone that supports the N-Gage 2.0 service; requires the N-Gage application to be installed on the phone in order to run.
Nokia phones that support the N-Gage application include the N73, N78, N81, N82, N93, N95, N96, and the Nokia XpressMusic 5320.
Updated: September 11, 2011