ONScripter (O-N-Scripter) is a program that interprets a script written for NScripter in its own way.

You have to prepare game data separately.
Create folders for each game under /sdcard/ons and place game data (nscript.dat, etc.) under those folders.
Place a truetype font file renamed as default.ttf at the same location as game data.
If you want to play video, install an appropriate video player such as MX Video Player.

Please see the following web page for more details.
http://onscripter.osdn.jp/onscripter.html
http://onscripter.osdn.jp/android/