President Choi Kim was the political leader of North Korea during Mercenaries: Playground of Destruction. He was unique in that he wanted peace with the South and tried to install a pro-western democratic government to unify Korea once again. He was the father of Ace of Spades, General Choi Song.
President Kim was sick of constant fighting with South Korea and wanted to exchange an olive branch, a peace settlement, to end the conflict. Kim wanted to create a pro-western government and unify North and South to bring Korea together again and improve relations with the west.
President Kim gathered many political leaders from both the North and South and got together to begin the peace agreements. They all went well and Korea was about to be re-unified, however, at a ceremony celebrating the final end to the ongoing Korean War, President Kim's patriotic, nationalist son and leader of the Korean Army, General Choi Song, disagreed greatly with the unification and saw the South as weak and did not want to be allied with the west and saw that his father had lost the vision of North Korea's greatness.
Using Division 39, a former secret state-sponsored mafia who were mostly made up of ex-members of Kim's cabinet to finance the plan, General Song then stormed the ceremony with a large group of insurgents in tow and killed all in attendance, with President Kim being killed by Song himself without hesitation. Nothing further was announced to the world and Kim was proclaimed dead by the rest of the world.
Although Kim was supposed dead, important footage was recovered from Kumchang-Ni while the mercenary was trying to capture the Ace of Hearts, Chul Kang, a secret video tape was found that contained extremely important footage. The video contained a meeting between General Song and the King of Spades in a snowy area.
They were talking about supposedly an interrogation with president Kim, and apparently he knew the proper codes to launch the missiles created by North Korea before the coup, President Kim would not divulge the information but Song believed he was ready to crack due to him being "weak-willed".
This new discovery spread hope through all of the Allied Nations, by studying the rock formations and level of snow in the video they could find out where Song was. After the mercenary had landed on the island where Song was, along with a column of AN M1 Tanks, they fought their way to the prison where Kim was being held and discovered that he truly was alive, but was in a critical condition after weeks of torture. The mercenary then called for an evacuation helicopter and AN reinforcements quickly arrived at the scene to help the mercenary and save Kim. After his recovery, Kim was most likely reinstated as the current President of North Korea.