The guest artist must attempt to guess mystery singers who are "good" and "bad" without hearing them sing. Mystery singers must partake on every round, at which they can receive help and advice from the celebrity panelists. After eliminating one to two mystery singers in each round, they would perform using real voice at the stage of truth. The last mystery singer standing will do duet-perform by guest artist. The original version has two gameplay formats: ;Original format Under the original format, the guest artist can simply eliminate mystery singers after every round concluded; and the last mystery singer will do duet-perform with. ;Star wars format Under the star wars format, ten former mystery singers were separated into two teams. For each round, a mystery singer is chosen for a "showdown". After this, the voting is done through audience majority, and the votes are accumulated for the winning team. ;Rewards The winning good singer receives a digital single release while the winning bad singer gets ₩5,000,000.
Rounds
There were six individuals or groups of mystery singers standing on the platform with its aliases to keep their identities concealed until its initial performance. ;Singer's visual
The guest artist have time to observe and examine each mystery singer based on their appearance. After this, a muted video of each mysyery singer that reveals only 0.3 seconds of their singing voice is played as an additional hint.
Each mystery singer is given two identities – as a good singer and as a bad singer. Only one of them is their real identity.
;Singer's speech
Each mystery singer introduces and tells its stories with their own voice.
;Singer's lip-sync
Every mystery singer performs a lip-sync of a song. good singers lip-sync to their own voice, while bad singers lip-sync to other's voices.
A mystery singer and a substitute lip-sync to the song together. Only one of them is the owner of the voice.
The mystery singer lip-syncs to the good singer's voice, then the bad singer's voice comes in the middle of the performance.
;Singer's verdict
Identify the good and bad singers within 100 seconds based on its true statement.
The guest artist must have then 100 seconds to make an interview with the remaining mystery singers before making the final decision, at which point is depending on every panelists' opinion and/or an audience's majority voting.
;Singer's evidence
A proof of each mystery singer's singing ability is shown on the screen. Good singers have their own evidences while bad singers had their evidences fabricated.
Three randomly selected panelists must hear the mystery singer's singing voice using a headphone. Afterwards, he or she must defend the mystery singer and convince the guest artist to choose him/her as the final mystery singer.
The hosts of the show have randomly assigned clues about the mystery singer. The guest artist must choose a clue for each mystery singer.
Seasons' overview
Episodes
Season 1
Season 2
Season 3
Season 4
Season 5
Season 6
Season 7
Ratings
In the table below, represent the lowest ratings and represent the highest ratings.
