Complex sentence: Gilbert created many successful adventure games at LucasArts, including the classic "The Secret of Monkey Island", until 1992, when he left the company to start Humongous Entertainment with LucasArts producer Shelley Day.
Split into simpler sentences: Gilbert created many successful adventure games at LucasArts, including the classic "The Secret of Monkey Island". In 1992 he left the company to start Humongous Entertainment with LucasArts producer Shelley Day.