There is only one file type that uses the .NGS extension:
Steins;Gate Game File
File used by Steins;Gate, a Japanese visual novel video game; contains video segments, such as the prologue, featured in the game; may also stores sounds referenced during gameplay; similar to the .MPG file.
|5pb. and Nitroplus Steins;Gate||Paid|
Updated: November 21, 2014