The Great Apocalypse

Apocalypse came suddenly on the year 2024. People who weren't born in the year 2005, 2006, and 2007 disappear. Monsters and many others beasts are now roaming the Earth. The late teens now need to defend themselves. A young American teen named Cyril, in his 17th year gained The Apocalyptic System which let him receive random ability everytime he kills a boss level monster or after he complete a high Tier quest.