Complex sentence: The Yeti have since appeared infrequently in flashbacks or cameo appearances, in addition to 1990s "Virgin Missing Adventures" novels and the 1995 Reeltime spin-off production "Downtime".
Split into simpler sentences: The Yeti have since appeared infrequently in flashbacks or cameo appearances. They also appear in the 1990s "Virgin Missing Adventures" novels and the 1995 Reeltime spin-off production "Downtime".