Tsetseg is the villainess of "Horseback Mountain", case #17 of Criminal Case: Save the World, the 3rd season of the crime solving game Criminal Case (release date January 14, 2016). She was a horse breeder who also offered horse riding lessons to tourists.
Tsetseg was questioned by the player and Carmen Martinez regarding the murder of Andrei Beloglazov, a satellite engineer working with terrorist organization SOMBRA to construct a satellite in order to control all the world's technology. Tsetseg initially claimed that Andrei was simply another tourist and that she had no idea what he was doing in Mongolia. Later on, though, Tsetseg confessed that she'd let Andrei ride one of her prized horses (a pure bred Mongol stallion) up Mount Khan. Andrei, however, wasn't experienced enough to guide the horse back down, ultimately leaving it on the mountain to die.
Eventually, the evidence pointed to Tsetseg being Andrei's killer, and she brought in for interrogation. While Carmen initially believed Tsetseg killed Andrei in revenge for causing her horse's death, Tsetseg eventually revealed her true motivation: she was a skilled hitwoman who had been hired by SOMBRA to kill Andrei to tie up loose ends. Tsetseg committed the murder on Mount Khan, donning a Mongolian mask before slashing Andrei with a sword. During her confession, Tsetseg chastised herself for her mistakes in Andrei's murder and stated that she'd planned on the job being her last before retiring to work on her family stables. Tsetseg was arrested and sentenced by judge Nigel Adaku to thirty years in prison, with Tsetseg refusing to say more about SOMBRA and further bemoaning how she'd let the temptation of another "adventure" got the better of her.