Genres
System apocalypse
LitRPG subgenre requiring both an apocalyptic inciting event and functioning system mechanics; the System's arrival is involuntary.
System apocalypse is a LitRPG subgenre that requires both an apocalyptic inciting event and functioning LitRPG mechanics; missing either disqualifies it. The System's arrival is abrupt and involuntary, with no chosen one and no willing tutorial entry, which is the key differentiator from standard "trapped in a game" setups. Growth is quantified (levels, stat points) rather than narratively implied.
The genre's continuity burden is unusually heavy: the world's rules change at chapter one, and every system announcement after that is canon.