Weird Rules: I Hear Everything's Voice

Seven years ago a black rain fell and pulled people into dungeons that run on stated rules. Lin Han, who has late-stage brain cancer and is dying of it, is taken into a training ground for those dungeons. There he finds he can hear the voices of objects, which tell him things the rules hide. He uses that and works out where the rules are lying to him, and he clears the trials built around greed and around envy. Surviving them cures the cancer. His parents then fall seriously ill, and to save them he enters a harder dungeon shaped as an old opera troupe. Inside it he meets Liu Xiyan, an heir of the troupe. The dungeon's last trial is the Mortal Guide test, and what the test actually is turns out to be the truth about where the dungeons came from. Passing it makes him a guide who can cross between the two worlds.