I create MSDD.
I have an age rating system called MSCR and it's on a scale from 1-10
1: Easy to understand language, and no blood or goryness. (Meant for children)
2: Games with a small amount of violence, or more complex themes (Minecraft goes here)
3-5: Are slightly worse but for different reasons:
3 - Lots of blood or violence
4 - Suggestive Themes
5 - Drug use
6: Uses "bad" language and may feature any 2 things from 2-5 (Meant for teens)
7: Same as 6 but with all three categories. (Meant for slightly older teens usually 14-16)
8: Possible Gambling, Possible Sexual scenes, extensive use of 2 or more of the previous categories (Meant for adults-mature teens, MSDD goes here)
9: Heavy adult content. (Meant for Adults, GTA V goes here)
10: Adult only, usually reserved for a porn game or such