The Dark Forest subtheme released in 1996 consisted of only 3 sets and were primarily only available in North America. Dark Forest is a somewhat continuation of the Forestmen subtheme which was discontinued in 1990 as it reused the same crest and used other environment structures such as forest hideouts.
The Castle theme is one of LEGO’s primary themes first introduced in 1978 and based around medieval life with castles and knights.