ONScripter (O-N-Scripter) is designed to interpret scripts written for NScripter in its own way.
You need to prepare game data separately.
Then, you need to create a folder for each game within the /sdcard/ons directory and place the game data (nscript.dat, etc.) in those folders.
You also need to place a TrueType font file named 'default.ttf' in the same location as the game data.
If you want to play videos, it's recommended to install a suitable video player such as MX Player.
Please see the following web pages for more detailed information.
https://ogapee.github.io/www/onscripter_en.html
https://ogapee.github.io/www/android/