This long-running and highly influential South Korean variety show, known for its unpredictable challenges and comedic cast, aired for over 12 years from 2005 to 2018, becoming a cultural phenomenon. What is the name of this program?

The program described, a highly influential South Korean variety show known for its unpredictable challenges and comedic cast, which aired for over 12 years from 2005 to 2018, is indeed Infinite Challenge (Review). This groundbreaking show premiered on April 23, 2005, initially as "Reckless Challenge" before being rebranded as "Infinite Challenge" in 2006, and concluded its remarkable run on March 31, 2018. It was broadcast on MBC TV and quickly became a cultural phenomenon, captivating audiences across South Korea.

Infinite Challenge is widely recognized as "Korea's first reality-variety show," a pioneering format that blended the humorous games typical of variety shows with the intimate, often unscripted style of reality television. The show's core comedic cast, led by the renowned host Yoo Jae-suk, along with members like Park Myung-soo, Jeong Jun-ha, and Haha, tackled a wide array of absurd, physically demanding, and often satirical challenges. These challenges ranged from intricate physical competitions and biennial song festivals with famous musicians to long-term projects such as bobsleigh training and historical recreations, consistently pushing the boundaries of entertainment.

The program's profound cultural impact earned it the moniker "the nation's variety show." It consistently achieved high viewership ratings, at one point drawing nearly 30 percent of South Korean television viewers. Beyond entertainment, Infinite Challenge often incorporated social commentary and educational elements into its unique segments, inspiring international adaptations and shaping the landscape of modern Korean television. Even after its conclusion, the show's legacy endures, with its innovative spirit and memorable moments continuing to influence variety programming.