Complex sentence: Since Ludum Dare 18, that occurred in August 2010, a more relaxed version was introduced, called the "Jam", which takes place concurrently with the main competition and allows for teams, unshared code, and an extended deadline of 72 hours.
Split into simpler sentences: Since Ludum Dare 18, which occurred in August 2010, a more relaxed version called the "Jam" was introduced. The Jam takes place concurrently with the main competition and allows teams, unshared code, and an extended deadline of 72 hours.